diff --git a/lib/index.js b/lib/index.js
index b842d9e..d000c86 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -31,6 +31,7 @@ Pleeease.prototype.process = function (css) {
         filter         = require('pleeease-filters'),
         rem            = require('pixrem'),
         pseudoElements = require('../lib/processors/pseudoElements'),
+        opacity        = require('../lib/processors/opacity'),
         mqpacker       = require('css-mqpacker'),
         prefixer       = require('autoprefixer-core'),
         minifier       = require('csswring');
@@ -47,6 +48,7 @@ Pleeease.prototype.process = function (css) {
         (opts = this.opts.filters)               ? filter(opts).postcss     : false,
         (opts = this.opts.rem)                   ? rem(opts).postcss        : false,
         (opts = this.opts.pseudoElements)        ? pseudoElements.processor : false,
+        (opts = this.opts.opacity)               ? opacity.processor        : false,
         (opts = this.opts.mqpacker)              ? mqpacker.processor       : false,
         (opts = this.opts.autoprefixer)          ? prefixer(opts).postcss   : false,
         (opts = this.opts.minifier)              ? minifier(opts).postcss   : false
diff --git a/lib/options.js b/lib/options.js
index 833882f..bc55cec 100644
--- a/lib/options.js
+++ b/lib/options.js
@@ -25,6 +25,7 @@ function Options () {
         'filters':              true,
         'rem':                  true,
         'pseudoElements':       true,
+        'opacity':              true,
 
         'import':               true,
         'mqpacker':             true,
diff --git a/lib/processors/opacity.js b/lib/processors/opacity.js
new file mode 100644
index 0000000..6207906
--- /dev/null
+++ b/lib/processors/opacity.js
@@ -0,0 +1,41 @@
+'use strict';
+
+/**
+ *
+ * Fallback opacity property
+ *
+ */
+module.exports.processor = function (css) {
+
+  var PROP         = 'opacity';
+  var PROP_REPLACE = 'filter';
+
+  // for each rules, each decl
+  css.eachRule(function (rule) {
+    rule.eachDecl(function (decl) {
+
+      if (decl.prop !== PROP) { return; }
+
+      // get amount and create value
+      var amount = Math.floor(decl.value * 100);
+      var VAL_REPLACE  = 'alpha(opacity=' + amount + ')';
+
+      // find if a filter opacity is already present
+      var isFilterAlreadyPresent = false;
+      rule.eachDecl(function (d) {
+        if (d.prop === PROP_REPLACE && d.value === VAL_REPLACE) {
+          isFilterAlreadyPresent = true;
+        }
+      });
+
+      // adds new porperty only if it's not present yet
+      if (!isFilterAlreadyPresent) {
+        rule.insertAfter(decl, {prop: PROP_REPLACE, value: VAL_REPLACE});
+      }
+
+    });
+  });
+
+  return css;
+
+};
\ No newline at end of file
diff --git a/test/features.js b/test/features.js
index 83ff249..e491c86 100644
--- a/test/features.js
+++ b/test/features.js
@@ -76,6 +76,17 @@ describe('Features', function () {
 
   });
 
+  describe('Opacity', function () {
+
+    it('should convert opacity into filter', function () {
+
+      // options
+      test('opacity', opts);
+
+    });
+
+  });
+
   describe('MQs', function () {
 
     it('should combine media-queries', function () {
diff --git a/test/features/opacity.css b/test/features/opacity.css
new file mode 100644
index 0000000..bfda4cb
--- /dev/null
+++ b/test/features/opacity.css
@@ -0,0 +1,10 @@
+.opacity {
+  opacity: .5;
+}
+.opacity {
+  opacity: .216708;
+}
+.opacity {
+  opacity: .5;
+  filter: alpha(opacity=50);
+}
\ No newline at end of file
diff --git a/test/features/opacity.out.css b/test/features/opacity.out.css
new file mode 100644
index 0000000..894bb3f
--- /dev/null
+++ b/test/features/opacity.out.css
@@ -0,0 +1,12 @@
+.opacity {
+  opacity: .5;
+  filter: alpha(opacity=50);
+}
+.opacity {
+  opacity: .216708;
+  filter: alpha(opacity=21);
+}
+.opacity {
+  opacity: .5;
+  filter: alpha(opacity=50);
+}
\ No newline at end of file