The present paper covers the comparison of two different configurations (square and circular)pin-fin heat sinks embedded with two different phase change materials (PCMs) namely paraffin wax and n-eicosane having different thermo-physical properties were carried out for passive cooling of electronic devices. The pin-fins, acting as thermal conductivity enhancers (TCEs), of 2 mm square and 3 mm circular fin thickness of constant volume fraction of 9% are chosen and input heat fluxes from 1.2 kW/m(2) to 3.2 kW/m(2) with an increment of 0.4 kW/m(2) are provided. Two different critical set point temperatures (SPTs) 45 degrees C and 65 degrees C are chosen to explore the thermal performance in terms of enhancement ratios, enhancement in operation time, latent heating phase duration, thermal capacity and conductance. The results show that 3 mm diameter of circular pin-fins has the best thermal performance in passive thermal management of electronic devices. (C) 2017 Elsevier Ltd. All rights reserved.