Abstract The H + D 2 reactive system is studied in the energy range 0.84 < E tr< 2.70 eV employing the l-in infinite-order sudden approximation. In contrast to a previous treatment, this study is carried out with the correct matching parameter. Integral and differential cross sections and opacity functions are calculated and compared with quasi-classical trajectory and experimental results. In most cases encouraging agreement is obtained. Discrepancies for the integral cross sections in the high-energy region (> 2 eV) are attributed to quantum effects. The results are analysed employing an angle oriented transition state theory.