The disclosure relates to a heat curable powder coating composition suitable for being cured at a temperature from 60 to 130° C. containing: a thermal initiation system and a resin system, wherein the reactivity of the thermal initiation system is such that the thermal initiation system provides a geltime between 2.5 and 1000 minutes at 60° C. in butane diol-dimethacrylate as measured according to DIN 16945 using 1 wt % of the thermal initiation system in 99 wt % of butane dioldimethacrylate, wherein the amount of thermal initiation system is chosen such that when the powder coating composition is applied to a substrate and cured at a temperature of 130° C. for 20 minutes.