A significantly active Pd-Pt/carbon electrocatalyst for polymer electrolyte membrane fuel cells was synthesized by microwave irradiation using a hollow core mesoporous shell (HCMS) carbon as catalyst support that was prepared by template replication of core/shell spherical silica particles and two different carbon precursors. Pt/Pd percent weight ratios on carbon support were varied as 20/0, 15/5, 10/10, 5/15 to 0/20. As the average pore diameter of the carbon support was increased from 3.02 nm to 3.90 nm by changing the type of the carbon precursor, fuel cell performances of the HCMS carbon based Pd-Pt bimetallic catalysts were improved significantly. (C) 2009 Elsevier B.V. All rights reserved.