This work is based on the combination of experiments and simulations to evaluate thermal contact resistance (TCR) at the interface between polymer melt and cavity surface directly in microinjection moulding process. Surface topography is considered to be one of the main factors in the evaluation of the TCR. Three sapphire windows with different surface roughnesses, which were analysed using a 3D laser measuring microscope, were used to represent one half of the cavity wall. The thermal properties of the sapphire are very similar to those of P20 mould steel, which means that heat flux through the sapphire will be similar to that of the steel mould. A special mould has been designed to allow non-contact temperature measurements of the polymer melt inside the cavity. A well established procedure for the detection of infrared radiation has been employed to obtain temperature measurements. The high speed infrared camera has been used to measure polymer surface temperature directly inside the cavity. The experimental work, which has been performed on Battenfeld Microsystem 50 microinjection moulding machine, has been validated by heat transfer simulations over a 3D finite element model using Abaqus simulation software.