The absolute emission probabilities of gamma rays from the decay of 238Np and 233Pa have been measured by an innovative method combining pile oscillation and neutron activation techniques. We obtained values of (24.99 ± 0.34)% and (37.79 ± 0.64)% for the 984.5- and 311.9-keV gamma rays from 238Np and 233Pa, respectively, in good agreement with the recommended values proposed by the Decay Data Evaluation Project (DDEP): (25.18 ± 0.13)% and (38.3 ± 0.5)%. The influence of gamma-ray emission probabilities from 238Np and 233Pa on neutron capture cross-section measurements of 237Np and 232Th, respectively, are discussed and tend to confirm the recommended values from the DDEP. A patent has been granted for this method.