The ORNL ion-atom merged-beams apparatus has measured benchmark electron capture cross sections for the multicharged ion O⁴⁺ on D from 0.61 eV/u to 369 eV/u (C. C. Havener, M. P. Nesnidal, M. R. Porter, and R. A. Phaneuf, Nucl. Instrum. Methods B 56/57 95 (1991)). Calculations of Gargaud et al. (1988) predict that capture to the 3d state dominates, especially below 200 eV/u. The effect of rotational coupling is predicted to be considerable. The present measurements are significantly lower than the predictions, the discrepancy on the order of the enhancement due to rotational coupling.