Highly durable platinum (Pt) catalysts for oxygen reduction reaction (ORR) were fabricated using pulverized isotropic pitch based activated carbon fibers as catalyst supports. We controlled the textural and structural properties of catalyst support by heat-treatment with various temperatures of 900, 1200, 1500, and 2000 degrees C. Crystallinity of the catalyst supports increased with increasing heat-treatment temperature, leading to an increase of conductivity. In addition, the catalytic activity and durability increased and the catalyst using carbon supports heat-treated at 1200 degrees C showed a comparable performance and superior durability to those of a commercial catalyst. It is suggested that an increase in crystallinity was attributed to prevent elimination of Pt and carbon support, which led to less degradation of catalytic activity and durability for ORR. This work showed the possibility of pitch based activated carbon fibers as a highly durable catalyst support.