Analysis of the spectral-luminescent properties of phenol and its derivatives has shown that quantum yield of fluorescence decreases in the series: phenol, 4-chlorophenol, 4-bromphenol. According to quantum-chemical calculations, the low quantum yield of fluorescence is caused by intercombination conversion which is more efficient than the radiation decay of the state S1 (kr = 3 107-1, kST = 108 s-1). Substitutions lead to the increase in the efficiency of i>S-T conversion, decrease in the quantum yield in 4-chlorophenol, and quenching of fluorescence in 4-bromophenol (gPh = 0.23, gCl-Ph = 0.09, gBr-Ph = 10-4). The efficiency of photolysis in phenol and its derivatives under the exposure to UV radiation was compared using both theoretical and experimental methods.