Magnetic field modulated pyrene-N,N-dimethylanilne exciplex fluorescence has been studied in reverse micelle of D2O/AOT/n-heptane. Results have been compared with those in H2O/AOT/n-heptane to understand the effect of deuterium on exciplex luminescence. Strikingly the extent of magnetic field effect (MFE) has been found to be much larger in D2O/AOT/n-heptane. The fluorescence lifetime of the exciplexes have been found to be larger in D2O/AOT/n-heptane than that in H2O/AOT/n-heptane. The stronger hydrogen bond strength in D2O compared to that of H2O has been identified to be the prime factor for the effect. Variation of the MFE with temperature in D2O/AOT/n-heptane and H2O/AOT/n-heptane has also been studied. (C) 2008 Elsevier B.V. All rights reserved.