The work presented is focused on the heat transfer coefficient (HTC) in microinjection moulding, a parameter which describes the heat flow between the polymer melt and the mould wall. The HTC is a dominant parameter in cooling simulation predictions. Understanding of heat flux during cooling phase is essential, as cooling behavior can have a significant influence on internal structure, morphology and resulting physical properties, yet the availability of HTC values for microinjection moulding is limited. A range of cooling curves were obtained for two materials, namely carbon black filled polypropylene and carbon black filled polystyrene using a special mould with a sapphire window which allowed surface temperature measurements during the cycle using a high speed infrared camera. The obtained cooling curves were statistically analysed and compared to simulation results. Microinjection moulding simulations were performed using Moldflow software where processing conditions were matched to the experimental parameters, including different melt temperatures, mould temperatures, injection speeds and packing pressure. Within Moldflow software two solvers, namely the conduction and flow solvers, were employed to obtain cooling profiles of the melt surface temperature. For both materials improvements in cooling prediction were observed with an increase of HTC values from 2500 W/m2C (default) to 7700 W/m2C.