We have applied the technique of picosecond laser spectroscopy to study the photodissociation of nitrobenzene at room temperature and 100mTorr. Three different photolysis pulses, λ2=250, 266, and 280nm, with a duration of 20–25ps, were used. The NO photofragment was detected via LIF between λ1=220 and 250nm. The profile of rotational population distribution shows a dependency on the photolysis wavelength and the delay time. The observed rotational population distributions are non-Boltzmann and bimodal for v″=0, 1, and 2.