The kinetics of growth and antibody formation of an anti–interleukin-2 producing hybridoma line were studied in suspension culture at temperatures ranging from 34°C to 39°C. Flow cytometry was used to determine the effect of temperature on the cell cycle. Maximum cell density and monoclonal antibody yield were observed at 37°C. The specific monoclonal antibody production rate was approximately constant throughout each batch experiment. Lower temperatures caused cells to stay longer in the G1-phase of the cell cycle, but temperature had only a marginal effect on the specific antibody production rate. Arresting of cells in the G1-phase by means of temperature was, therefore, not suited for enhanced monoclonal antibody production. Rather, antibody production for this hybridoma was directly linked to viable cell concentration. © 1992 John Wiley & Sons, Inc.