Dynamics of relaxation from higher electronic excited states was studied for 9,10,19,20-tetraalkylporphycenes with methyl and propy, substitutents. Depopulation Of S-3/S-4 Soret states leading into S-2/S-1 Q levels occurs in about 50 fs. This time is similar, or even shorter than that recently determined for porphyrin, even though the Q-Soret energy separation in the latter is about twice smaller than in porphycenes. The time constant for H or D transfers are shorter than 50 fs indicating very low energy barriers to their transfer. The nonradiative rate constants of both derivatives are related to the motion of the alkyl chain. (c) 2006 Elsevier B.V. All rights reserved.