Production of electron‐beam pulses with a 700‐ps FWHM duration, using laser‐photoelectron emission from a cold trioxide cathode in a 3‐MV Van de Graaff accelerator has been demonstrated. At 70‐kW laser power (&lgr;=337.2 nm) a current of about 1 mA has been measured which means a cathode quantum efficiency of 10−7. An electron transit time jitter of about 40 ps has been measured, to be attributed to voltage fluctuations on the accelerator tube electrodes resulting from the charging belt system. The results are discussed with respect to the feasibility to produce short pulses with a 1‐nC total charge, taking into account the quantum efficiency of 10−4measured in a test setup for the cold trioxide cathode. Larger quantum efficiency for the accelerator cathode and decrease of the transit time jitter are the main goals set for development of the Van de Graaff accelerator as a radiation source for very high time‐resolution experiments in radiation chemistry and physics.