Femtosecond (fs) and nanosecond (ns) transient absorption (TA) and single pulse transient resonance Raman spectroscopic investigation, of the intermediates after laser photolysis, of 4-phenoxyphenyl azide in acetonitrile and mixed aqueous solution is reported. fs-TA results show that the singlet 4-phenoxyphenylnitrene was produced immediately after photolysis of the azide. Then, the singlet nitrene underwent. intersystem crossing (ISC) and ring expansion to generate triplet nitrene and ketenimine in acetonitrile with t = 346 ps or protonation in Mixed aqueous solution with t = 37 ps, respectively, a little Slower than the counterparts of the methoxy one (108 and 5.4 ps for ISC and protonation processes, respectively): The transient Raman spectrum combined density functional theory (DFT) calculation predicting the Structure and vibrational-frequencies suggested that phenoxyphenylnitrenium ion has a comparable quinoidal character to that of methoxy- and ethoxy-phenylnitrenium ions: All of these results indicated that the phenoxy substitution has some impact on the reactivity of phenylnitrene but a slight influence on the structure of phenylnitrenium ion.