The photodissociation of HMn(CO)(3)(dab) has been studied through contracted configuration interaction (CCI) calculations on top of CASSCF wave functions for the metal-hydrogen bond homolysis and the photodissociation of an axial carbonyl ligand. The corresponding potential energy curves (PEC) connect the ground and excited states of the reactant to the ground and excited states of the primary products. The calculations were carried out under C-s symmetry constraint with a basis set that is at least of double-zeta quality. The multinference CCI calculations that correlate the 3d electrons and the two electrons of the Mn-H bond were based on CASSCF wave functions with eight electrons in ten active orbitals (3d(yz), 3d(x -y)(2), 3d(xz), Mn-sigma-H, (sigma)*Mn-H, 3d(xy), 4d(yz), 4d(x -y)(2), 4d(xz), pi*) optimized for the required state. From the shape of the PEC it appears that the interaction between the two lowest a(3)A’(d(xz) --> pi*) and b(3)A’(d(x -y)(2) --> pi*) metal-to-ligand charge transfer (MLCT) excited states and the C(3)A’ (sigma --> pi*) ligand-to-ligand charge transfer (LLCT) dissociative state plays a key role in the homolysis mechanism.