There is provided an extended release pharmaceutical composition comprising from about 200 mg to about 1000 mg of entacapone or salts thereof, optionally with other pharmaceutically acceptable excipients. The invention also provides an extended release pharmaceutical composition comprising triple combination of from about 30 mg to about 300 mg of levodopa, 10 mg to about 100 mg of carbidopa and 200 mg to about 1000 mg of entacapone or salts thereof, optionally with other pharmaceutically acceptable excipients. The invention also relates to process of preparation of such compositions.