The structural performance of a bituminous or macadam pavement depends upon the effectiveness of the compaction of the hot paving materials during the pavement's construction. To be effective the compaction process should be completed before loss of heat causes the paving material to become stiff and unworkable. It is therefore important to know the rate of cooling of the hot material after laying in order to ensure that adequate compactive effort is applied to achieve the desired level of compaction. This report describes the development of a computer model designed to stimulate the cooling behaviour of hot paving material after laying. The accuracy of the model is examined by comparing experimentally determined colling curves of hot materials laid under a variety of ambient conditions at five test sites, with cooling curves predicted by the model for these same sites. The comparison shows good agreement between experimental and predicted cooling curves. The rates of heat loss through the surfaces and bases of hot mix layers are examined using the model and the effect on cooling rates of heated supporting layers, of increased layer thickness, and of variations in climatic conditions are studied. Simulation results show that initially the larger rate of heat loss from the hot layer is that through the bottom of the layer but that with increasing time after laying the surface rate of heat loss becomes dominant. Heating of the cold substrate reduces significantly the rate of heat loss through the bottom of the layer. Increasing the lift thickness marginally increases the overall rate of heat loss but because the thicker lifts lose a smaller proportion of their initial heat content they maintain a higher temperature for longer periods than the thinner lifts. Differences between mid-layer cooling rates for the extremes of climate considered are of the order of 1§C per minute for a 30 mm thick layer, reducing to 0.5§C per minute for 100mm thick layers.