Dehydration effects on gelatin films of the D96N mutant bacteriorhodopsin (BR) and wild-type BR were studied. Unlike the wild-type BR films, wherein dehydration to 12% humidity results in an approximate 200-fold increase in the lifetime of the M state, D96N BR films dehydrated to the same extent have been shown to exhibit only a 17- to 20-fold increase in the lifetime of the M state. Chemically-enhanced D96N BR films possess a total bleaching efficiency of the initial-to-M;state transition that is close to theoretical maximum (1.0) over a wide range of relative humidity (35 to 85%). This provides an additional benefit to the D96N BR films as a material for storage and retrieval of optical information.