Ground tire rubber was devulcanizated at 180-280 degrees C and 200-600 rpm in co-rotating twin extruder with a special configuration of the plasticizing unit, enabling generation of considerable shear forces. The devulcanizates were then vulcanizated with S at 150 degrees C and studied for mech. properties. Response surface method was used in the study. Math. model was detd. as a function of devulcanization conditions (barrel temp., screw rotational speed, feed rate).