Information on fermentation process kinetics is potentially valuable for the improvement of batch process performance; it is essential for continuous process design. An empirical era mi nation of rate patterns in various fermentations discloses three basic types: (1) ＇growth associated＇ products arising directly from the energy metabolism of carbohydrates supplied, (2) indirect products of carbohydrate metabolism and (3) products apparently unrelated to carbohydrate oxidation. Effects of operating variables on the primary kinetic processes, growth, sugar utilization and antibiotic formation, in the penicillin process, illustrate the special nature of this type.