Reactions of N-14(+)(P-3), N-15(+)(P-3), and Kr+ with propane, propene, and propyne were studied using the selected ion flow tube, SIFT, technique. Thermal rate constants in all N+/C-3 systems were k = (2 +/- 0.4) x 10(-9) cm(3) molecule(-1)s(-1) close to the collisional rate constants. With propane and propene, only hydrocarbon ions were found among the products of reactions with N+; in propyne about 15% of the products were N-containing ions (C3H2N+, C2H4N+, C2H3N+, C2H2N+), and the rest were hydrocarbon ions. A comparison with product ions from electron transfer between Kr+ (of recombination energy similar to that for N+(P-3)) and the C-3 hydrocarbons and further analysis of the results led to an estimation of an approximate ratio of electron transfer vs hydride-ion transfer reactions leading to the hydrocarbon product ions: in propane the ratio was 2:1, in propene 3:1, and in propyne 5:1. A fraction of product ions resulted from reactions leading to the excited neutral product N*.