Time-independent quantum reactive scattering studies are performed for the X + O-2 -> OX + O reactions, where X = Mu, H, D and T are atomic hydrogen isotopes, using the accurate CHIPR potential energy surface (Varandas, 2013) and the popular ABC code. J-shifting thermal rate coefficients have been computed, thence extending our recently reported (Teixidor and Varandas, 2015) values for the reaction H(S-2) + O-2(3 Sigma(-)(g)) -> OH((2)Pi) + O(P-3). The results are compared with each other and the best experimental and theoretical data available in the literature, with the effect of isotopic substitution on state-specific rate constants being highlighted. (C) 2015 Elsevier B.V. All rights reserved.