The studies have reported that addition of nutrients improve bacterial hydrocarbon degradation (Boopathy, 2000, Röling et al., 2002 and Xu and Obbard, 2004); but no such work exists in the domain of microbial photophysiology, more specifically in hydrocarbon biodegradation. The objective of present study was to investigate the effect of illuminance (light flux), nutrients and time duration on hydrocarbon degradation and biomass production by variant bacterial species. Diesel oil due to multifaceted composition, containing cycloparaffins, paraffins, aromatic and olefinic hydrocarbons with carbon numbers predominantly in the range of C9 to C25, was used for the degradation study. To the best of authors' knowledge this is the first report of bacterial photophysiology and its effect on hydrocarbon degradation.