The effects of operating parameters on the steady-state heat flux and surface temperature at several locations on the cylinder head of a single-cylinder spark-ignition engine were investigated. The local heat flux was found to be strongly affected by engine speed and volumetric efficiency. Air-fuel ratio and spark timing had comparatively smaller effects. Coolant temperature, in the range of this study (300-380 K), had no effect on the average heat flux. Both the heat flux and the surface temperature varied considerably with the location of measurement. Except at very rich mixtures, the average heat flux was found to vary as the 0.65 power of the rate of fuel consumption.