Measurements of the magnetic field dependence of Fiske steps and ’’zero‐field’’ steps in Nb–Nb oxide–Pb Josephson junctions are described. By the use of a simple variable dc bias scheme, the measured ac volt‐ampere characteristics are made to clearly exhibit the step structure even in the presence of a large dc Josephson current. A comparison with the theory of Kulik for the magnetic field dependence of Fiske steps is shown and the correlation is very good for smallL/&lgr;jratios. Deviations for larger ratios include the appearance of zero‐field steps.