Edit in JSFiddle

.img{
    width:107px;
    height: 107px;
    display:block;
    background: url('http://i63.tinypic.com/5lzzp1.png') 0 0 no-repeat;
    -webkit-transition-duration: 0.8s;
    -moz-transition-duration: 0.8s;
    -o-transition-duration: 0.8s;
    transition-duration: 0.8s;
    -webkit-transition-property: -webkit-transform;
    -moz-transition-property: -moz-transform;
    -o-transition-property: -o-transform;
    transition-property: transform;
    overflow:hidden;
}
.img:hover{
    -webkit-transform:rotate(360deg);
    -moz-transform:rotate(360deg);
    -o-transform:rotate(360deg);
    transform:rotate(360deg);
}