Abstract: A method for the production of highly-active rubber powder from old tires and scrap vulcanised rubber articles based on various rubbers by 2-stage thermo-mechanical treatment in an extruder. This involves (a) fine pulverisation and (b) sharp reduction of the volume stress. An apparatus for the production of highly-active rubber powder includes a cylindrical housing with feed and discharge connections, a compression zone and pulverisation zone(s), each with a compression screw with grooves decreasing in depth in the machine direction and a rotating coaxial activator with grooves on its outer working surface, the housing, screw and activator being provided with cooling elements.