diff --git a/spec/j2x_spec.js b/spec/j2x_spec.js
index be0aa81e..2ab00f54 100644
--- a/spec/j2x_spec.js
+++ b/spec/j2x_spec.js
@@ -483,4 +483,117 @@ describe("XMLBuilder", function() {
         expect(result).toEqual(expected);
     });
 
+    it("should suppress null attributes in the xml when format is true and ignoreAttributes is false", function () {
+        const jObj = {
+            "list": {
+                "item": [
+                    "one",
+                    { "#text": "two" },
+                    { "#text": "three", "@_attr": null }, // only one null attr
+                    { "#text": "four", "@_attr": "foo", "@_attr1": null }, // one defined attr and one null attr
+                    { "#text": "five", "@_attr": null, "@_attr1": "baz" }, // one null attr and one defined attr
+                    { "#text": "six", "@_attr": "foo", "@_attr1": "baz" }, // all defined attrs (more than one)
+                    { "#text": "seven", "@_attr": null, "@_attr1": null }, // all null attrs (more than one)
+                ]
+            }
+        };
+        const builder = new XMLBuilder({
+            ignoreAttributes: false,
+            format: true
+        });
+        const result = builder.build(jObj);
+        const expected = `
+        <list>
+            <item>one</item>
+            <item>two</item>
+            <item>three</item>
+            <item attr="foo">four</item>
+            <item attr1="baz">five</item>
+            <item attr="foo" attr1="baz">six</item>
+            <item>seven</item>
+        </list>`;
+
+        expect(result.replace(/\s+/g, "")).toEqual(expected.replace(/\s+/g, ""));
+    });
+
+    it("should suppress null attributes in the xml when format is false and ignoreAttributes is false", function () {
+        const jObj = {
+            "list": {
+                "item": [
+                    "one",
+                    { "#text": "two" },
+                    { "#text": "three", "@_attr": null }, // only one null attr
+                    { "#text": "four", "@_attr": "foo", "@_attr1": null }, // one defined attr and one null attr
+                    { "#text": "five", "@_attr": null, "@_attr1": "baz" }, // one null attr and one defined attr
+                    { "#text": "six", "@_attr": "foo", "@_attr1": "baz" }, // all defined attrs (more than one)
+                    { "#text": "seven", "@_attr": null, "@_attr1": null }, // all null attrs (more than one)
+                ]
+            }
+        };
+        const builder = new XMLBuilder({
+            ignoreAttributes: false,
+            format: false
+        });
+        const result = builder.build(jObj);
+        const expected = `<list><item>one</item><item>two</item><item>three</item><item attr="foo">four</item><item attr1="baz">five</item><item attr="foo" attr1="baz">six</item><item>seven</item></list>`;
+
+        expect(result).toEqual(expected);
+    });
+
+    it("should suppress undefined attributes in the xml when format is true and ignoreAttributes is false", function () {
+        const jObj = {
+            "list": {
+                "item": [
+                    "one",
+                    { "#text": "two" },
+                    { "#text": "three", "@_attr": undefined }, // only one undefined attr
+                    { "#text": "four", "@_attr": "foo", "@_attr1": undefined }, // one defined attr and one undefined attr
+                    { "#text": "five", "@_attr": undefined, "@_attr1": "baz" }, // one undefined attr and one defined attr
+                    { "#text": "six", "@_attr": "foo", "@_attr1": "baz" }, // all defined attrs (more than one)
+                    { "#text": "seven", "@_attr": undefined, "@_attr1": undefined }, // all undefined attrs (more than one)
+                ]
+            }
+        };
+        const builder = new XMLBuilder({
+            ignoreAttributes: false,
+            format: true
+        });
+        const result = builder.build(jObj);
+        const expected = `
+        <list>
+            <item>one</item>
+            <item>two</item>
+            <item>three</item>
+            <item attr="foo">four</item>
+            <item attr1="baz">five</item>
+            <item attr="foo" attr1="baz">six</item>
+            <item>seven</item>
+        </list>`;
+
+        expect(result.replace(/\s+/g, "")).toEqual(expected.replace(/\s+/g, ""));
+    });
+
+    it("should suppress undefined attributes in the xml when format is false and ignoreAttributes is false", function () {
+        const jObj = {
+            "list": {
+                "item": [
+                    "one",
+                    { "#text": "two" },
+                    { "#text": "three", "@_attr": undefined }, // only one undefined attr
+                    { "#text": "four", "@_attr": "foo", "@_attr1": undefined }, // one defined attr and one undefined attr
+                    { "#text": "five", "@_attr": undefined, "@_attr1": "baz" }, // one undefined attr and one defined attr
+                    { "#text": "six", "@_attr": "foo", "@_attr1": "baz" }, // all defined attrs (more than one)
+                    { "#text": "seven", "@_attr": undefined, "@_attr1": undefined }, // all undefined attrs (more than one)
+                ]
+            }
+        };
+        const builder = new XMLBuilder({
+            ignoreAttributes: false,
+            format: false
+        });
+        const result = builder.build(jObj);
+        const expected = `<list><item>one</item><item>two</item><item>three</item><item attr="foo">four</item><item attr1="baz">five</item><item attr="foo" attr1="baz">six</item><item>seven</item></list>`;
+
+        expect(result).toEqual(expected);
+    });
 });
diff --git a/src/xmlbuilder/json2xml.js b/src/xmlbuilder/json2xml.js
index 813043f3..9dae3472 100644
--- a/src/xmlbuilder/json2xml.js
+++ b/src/xmlbuilder/json2xml.js
@@ -80,10 +80,19 @@ Builder.prototype.j2x = function(jObj, level) {
   let val = '';
   for (let key in jObj) {
     if (typeof jObj[key] === 'undefined') {
-      // supress undefined node
+      // supress undefined node only if it is not an attribute
+      if (this.isAttribute(key)) {
+        val += '';
+      }
     } else if (jObj[key] === null) {
-      if(key[0] === "?") val += this.indentate(level) + '<' + key + '?' + this.tagEndChar;
-      else val += this.indentate(level) + '<' + key + '/' + this.tagEndChar;
+      // null attribute should be ignored by the attribute list, but should not cause the tag closing
+      if (this.isAttribute(key)) {
+        val += '';
+      } else if (key[0] === '?') {
+        val += this.indentate(level) + '<' + key + '?' + this.tagEndChar;
+      } else {
+        val += this.indentate(level) + '<' + key + '/' + this.tagEndChar;
+      }
       // val += this.indentate(level) + '<' + key + '/' + this.tagEndChar;
     } else if (jObj[key] instanceof Date) {
       val += this.buildTextValNode(jObj[key], key, '', level);
@@ -176,7 +185,8 @@ Builder.prototype.buildObjectNode = function(val, key, attrStr, level) {
       tagEndExp = "";
     }
   
-    if (attrStr && val.indexOf('<') === -1) {
+    // attrStr is an empty string in case the attribute came as undefined or null
+    if ((attrStr || attrStr === '') && val.indexOf('<') === -1) {
       return ( this.indentate(level) + '<' +  key + attrStr + piClosingChar + '>' + val + tagEndExp );
     } else if (this.options.commentPropName !== false && key === this.options.commentPropName && piClosingChar.length === 0) {
       return this.indentate(level) + `<!--${val}-->` + this.newLine;