Two different poly(organophosphazene)s-bearing single-substituents (two cinnamyloxide side groups per repeating unit) and phnenoxide-co-substituents (one phenoxide and one cinnamyloxide group per repeating unit) were prepared to study their photochemical reaction behavior. Structural formulas confirmed by the NMRs (H-1, P-31) and IR were -[NP(OCH2CH = CH - C6H5)(2)](n) - (I) and -[NP(OCH2CH = CH - C5H5)(0.8)(O -C6H5)(1.2)](n) - (II). Molecular characterization yielded <(M-w)over bar>s of the order of 10(3) kg/mol for both the polymers. The onset temperature of decomposition found by TGA was about 250 degrees C. DSC measurements gave TgS as 1 degrees C for I and 3 degrees C for II. Their photolytic crosslinking behaviors were monitored by UV spectroscopy. The single-substituents polymer I showed a faster rate of photo reaction than the polymer II. The potential use for practical photosensitive application is considered to be greater for the polymer I.