The kinetics of growth, lactic acid and nisin production and substrate consumption by Lactococcus lactis subsp. lactis SM526 were studied in different pH. Growth, lactic acid and nisin production were modelled using a simple logistic equation while substrate consumption was foud to be a function of growth and lactic acid production rate. The optimal pH for growth and lactic acid production was 7.0 while it was 6.5 for nisin production according to the models developed.