Avalanchep–nphotodiodes with uniform breakdown over the junction area are known to be capable of single‐photon detection. An experimental study has been performed on the temporal resolution of these single‐photon avalanche diodes (SPADs) in measurements of the shape of ultrashort light pulses. By using an active‐quenching circuit, pulsed operation of the device has been obtained in accurately controlled conditions, avoiding spurious effects met in previous passive‐quenching circuits. Laser pulses with durations down to 150 ps FWHM have been used; the results obtained show that the resolution is remarkably better than this value. Performances and limitations of SPADs are discussed; temporal resolutions of a few tens of picoseconds may be expected.