The response function of 50 mm diameter deuterated (C 6D 6), plastic (NE102A) and liquid (NE213) scintillators have been measured below 6 MeV deuteron/proton energies using a 241AmBe source. Also the energy resolution of C 6D 6 scintillator was measured using a gamma-gamma coincident technique. The energy resolution of the C 6D 6 scintillator varies from 21.7 to 11.9% over 0.34–1.1 MeV electron energy range. The response function of the C 6D 6 scintillator agrees within 1–6% with that of Bovet et al. For the 50 mm NE102A and NE213 detectors, the response functions data agree with the published result of 125 mm NE102A and NE213 detectors. In the energy range below 5 MeV, the light output of the C 6D 6 scintillator is 17–24% lower than that of the NE213 detector. As the deuteron energy increases above 5 MeV, the difference between the light outputs of the two detectors starts to decrease up to 9 MeV, where light outputs of both detectors correspond to the same electron energy. This trend in difference of light output of C 6D 6 and NE213 scintillator is consistent with the published results of light output for C 6D 6 and C 6H 6 scintillators.