Biofilm development on surfaces exposed to aqueous environments usually causes an increase in fluid frictional resistance, heat transfer resistance, and corrosion which are of major concern to the water supply and power industries. The objective of this study was to investigate the effect of temperature, an important environmental factor, on the biofilm processes. A tubular fouling reactor system was used for this experimental study. Trypticase Soy Broth was added to the reactors providing the necessary growth requirements for a mixed culture of four bacterial species. A model with the appropriate material balances was developed for the experimental system. Six different temperatures (15-5°C) were tested and their effects on the rate coefficients are reported. An optimum temperature range for biomass growth and for the microbial process occurring within the biofilm was found.