Abstract: Provided herein are solid state forms of paliperidone salts, processes for preparation, pharmaceutical compositions, and method of treating thereof. Paliperidone is represented by the following structural formula (I): More particularly, provided are solid state forms of paliperidone acid addition salts, wherein the acid counter ion is provided by an acid selected from the group consisting of L-(+)-tartaric acid, p-toluenesulfonic acid, maleic acid, oxalic acid, fumaric acid, acetic acid and malic acid. Provided also herein is a process for preparing substantially pure paliperidone free base using the solid state forms of paliperidone salts.