We studied absorption and fluorescence spectra and decays of pentacene (Pc) in Shpol'skii matrices of n-heptane (C-7), n-nonane (C-9), n-decane (C-10), n-dodecane (C-12), n-tetradecane (C-14) and n-hexadecane (C-16) in the temperature range 1.7-200 K. The fluorescence quantum yields of Pc in C-12, C-14 and C-16 at 1.7 K were determined to be 20 +/- 6%, 26 6% and 22 6%, respectively. The kinetic analysis provided values of the radiative, internal conversion and intersystem crossing rate constants for the relaxation channels of the S, state of Pc in different matrices. Calculated fully saturated emission rates of single molecule were in very good relation with previous observation of single Pc molecules in Shpol'skii matrices. (C) 2002 Published by Elsevier Science B.V.