New photochromic 10’-substituted spiro[indoline-naphthoxazines] were synthesized and spectrokinetic parameters determined. Introduction of a substituent on the 10’-position have no significant influence an maximum wavelength absorption but the fading rate constant is highly increased. According to semi-empirical calculation, this behavior could be due to Steric hindrance occuring, on the open form, between the methyl group linked on the indolinic nitrogen and the 10’-substituent.