This experimental study investigates the effect of passive cooling of electronic devices using a latent heat storage unit (LHSU) filled with n-eicosane as phase change material (PCM),under steady-state and transient heating operations. A pin-fin heat sink of square configuration, made of aluminum, pin fins acted as a thermal conductivity enhancers (TCEs), is used to augment the rate of heat transfer through n-eicosane which has low thermal conductivity. A range of input heating loads from 1.2-2.8 kW/m(2) with an interval of 0.4 kW/m(2) are applied at the base of LHSU, filled at three different volumetric fractions of n-eicosane, to quantify the steady-state and transient heat transfer characteristics for different operation modes for reliable passive cooling of electronics. The results are reported under two phases i.e. steady-state and transient heating, and thermal performance of LHSU is elucidated in terms of enhancement in operation time, enhancement ratio, effect of PCM amount and various usage modes under different heating loads. (C) 2018 Elsevier Ltd. All rights reserved.