A study of both the singlet and triplet potential energy surfaces of the [H-3, P-2](+) system has been carried out using the G2 procedure. Various stable structures along with a number of reaction mechanisms for the reaction of both the D-1 and P-3 electronic states of P+ with phosphine have been elucidated. The most stable isomer on the singlet potential energy surface, which corresponds to the species resulting from a hydrogen migration in the P+-PH3 complex, lies 127.3 kcal/mol below the reactants level, P+(D-1) + PH3((1)A(1)). On the triplet surface, on the other hand, the P+-PH3 ion-molecule complex is the most stable isomer, 84.4 kcal/mol below P+(3P) + PH3((1)A(1)). Various reaction paths for both the molecular and atomic hydrogen elimination have been fully characterized. For both spin multiplicities the H-2 abstraction is found to be favored with respect to H abstraction, in full agreement with available experimental data. Finally, we have also discussed the hydrogen and/or charge-transfer reaction between singlet D-1 and triplet P-3 states of P+ with phosphine.