Quantum-mechanical close-coupling calculations for state-to-state cross-sections and thermal rate coefficients are reported for H-2 + H-2 collisions. Two recently developed potential energy surfaces (PESs) for the H-2-H-2 system are applied, namely, the global potential surface from the work [A. I. Boothroyd et al., J. Chem. Phys., H 6 (2000) 666], and a restricted, model surface from the work [P. Diep and J.K. Johnson, J. Chem. Phys. 113 (2000) 3480; P. Diep, J.K. Johnson, J. Chem. Phys. 112 (2000) 4465]. The low temperature limit is investigated. We found significant differences in cross-sections and corresponding thermal rate coefficients calculated with these two PESs. (c) 2006 Elsevier B.V. All rights reserved.