The excited-state dynamics of crystalline ClAl phthalocyanine colloidal particles have been studied by means of picosecond and femtosecond absorption spectroscopy. In the measured relaxation dynamics, the initial excited-state evolution, taking place during the first picosecond after excitation, was distinguished from the overall exciton decay. Excitation transfer between different molecular species is suggested to be the most probable reason to the initial (less than or equal to 1 ps) excited-state dynamics. Exciton decay was found to be dominated by exciton-exciton annihilation with a t(-1/2) time dependence of the excited-state population, suggesting a one-dimensional exciton diffusion. A 0.2-1 ps intermolecular exciton hopping time was determined from the annihilation dynamics.