Edit in JSFiddle

<a href="#"><img src="http://goinkscape.com/wp-content/uploads/2015/07/twitter-logo-final.png"></a>
a img {
  height:40px;
	width:40px;
   transition: height 0.5s, width 0.5s;
   -webkit-transition: height 0.5s, width 0.5s;
  }
a:hover>img {
  height:60px;
	width:60px;  
   transition: height 0.5s, width 0.5s;
   -webkit-transition: height 0.5s, width 0.5s;
  }