The model presented in this work demonstrates the combination of a cell-cycle model with a model describing the growth and conversion kinetics of hybridoma cells in a steady-state continuous culture. The cell-cycle model is based upon a population balance model as described by Cazzador et al. and assumes the existence of a cycling-and apoptotic-cell population, which together form the viable-cell population. In this part the fraction of apoptotic cells, the age distribution of the cycling-and apoptotic-cell population, the mean volume and biomass content per cell of the cycling, apoptotic, and viable cells, and the specific growth and death rates of the cells are calculated. The metabolic part consists of a Monod-type growth equation, four elemental balances, an equation assuming a constant yield of ammonia on glutamine, an equation for product formation, and the relation of Glacken for energy production. Furthermore, a maintenance-energy model for the consumption of glucose and glutamine is introduced, which combines the approaches of Herbert and Pirt into one model in a way similar to Beeftink et al. For energy consumption a Pirt model is assumed. The model is capable of predicting trends in steady-state values of a large number of variables of interest like specific growth rate, specific death rate, viability, cell numbers, mean viable-cell volume, and concentrations and conversion rates of product, glucose, glutamine, lactate, and ammonia. Also the concentrations and conversion rates of oxygen and carbon dioxide are qualitatively predicted. The values of the model predictions are generally close to experimental data obtained from literature.