The H+N 3 channel in the ultraviolet photodissociation of HN 3 has been investigated from 190 nm to 248 nm using the high-n Rydberg H-atom time-of-flight technique. Product translational energy distributions as well as product angular anisotropy parameters were determined for the H+N 3 channel at different photolysis wavelengths. N 3 vibrational state distribution has also been derived from the product translational energy distribution at these wavelengths. Above photolysis wavelength 225 nm, HN 3 predominantly dissociate through the repulsive state. Below 225 nm, a new slow channel starts to appear at 220 nm in addition to the existing channel. This channel is attributed to a ring closure dissociation channel to produce the cyclic N 3 product. As photolysis energy increases, this new channel becomes more important.