The effect of ionising radiation on copper(II) phthalocyanine 3,4′,4′′,4′′′ tetrasulfonic acid, tetrasodium salt (Cu(II)tspc4-) in aqueous as well as in water-methanol solutions has been studied. The determined yields of complex decomposition (measured on the basis of absorption decay) depend on the composition of matrices and the dose applied. The rate constant of electron scavenging by Cu(II)tspc4-, k = (1.3 ± 0.1) × 1010 M-1 s-1 in methanol-water (2:8 v/v) solutions has been determined using the pulse radiolysis technique. The rate constant k = (1.16 ± 0.1) × 1010 M-1 s-1 of scavenging of OH radicals applying the competion method with p-nitrosodimethylaniline (pNDA) has been determined in aqueous solutions.