The invention is for an improved process for of production of risperidone of formula (I) which comprises the steps of : (a) reacting a halo compound with an oxime ín a solvent and a base at 10-40°C; (b) refluxing the reaction mixture of step (a) for 4- 10 hours; (c) adding base to the cooled refluxed mixture of step (b) whileto maintaining the temperature at 20-40°C for 10-18 hours; (d) filtering and drying the risperidone thus obtained and (e) optionally purifying risperidone obtained in step (d). The invention also discloses a new polymorphic variety of risperidone namely, risperidone form T1 having its characteristic X-ray diffraction pattern and IR data.
