The effect of metal sheet resistance on capacitance measurements of Schottky barriers is investigated through modelling. The calculations show that when the capacitance is determined by conventional ac impedance measurements, the value obtained is less than the true capacitance when the metal sheet resistance is high. The 1/C2versusVplot will be nonlinear for extreme cases, but remains linear even for metal films with quite high resistivities. In the linear regime, the curves for different resistances will have a near identical slope but will be shifted along the 1/C2axis. This causes the barrier height to be overestimated. The error increases with increasing metal resistances. The series resistance determined fromI‐Vplots may not necessarily indicate whether the metal sheet resistance is detrimental for capacitance measurements. ©1995 American Institute of Physics.