The present invention provides a new polymorph Form I of Teriflunomide sodium and a process for preparation thereof. The present invention provides an amorphous form of Teriflunomide sodium and a process for preparation thereof. The present invention provides a new polymorph Form I of Teriflunomide potassium and a process for preparation thereof. The present invention provides an amorphous form of Teriflunomide potassium and a process for preparation thereof. The present invention also provides particle size of Teriflunomide and its salts.