: The present invention relates to solid forms of (±)-O-desmethyivenlafaxine salts, processes for preparation, pharmaceutical compositions, and method of treating thereof. More particularly, the present invention provides solid forms of acid addition salts of (±)-O desmethylvenIafaxine wherein the acid counter ion is provided by an acid selected from the group consisting of oxalic acid, benzoic acid and lactic acid. No. of Pages : 48 No. of Claims : 33