The objective of this study is to examine the potential of off-line biomass monitoring methods for the real-time prediction of viable cell density and viable cell volume in Chinese hamster ovary cell cultures. This work focuses on the use of Biomass Monitor for the monitoring of biomass. Two dual frequency settings and 2 temperatures were examined. The effects of interferences when the Biomass Monitor probe is present in a bioreactor are also investigated. The feasibility of constructing a prediction model for viable cell density and viable cell volume for in-line use is examined as there is an increased focus on monitoring techniques that adhere to the guidance in the United States Food and Drug Administration’s Process Analytical Technology framework. It was found that interferences to the Biomass Monitor include proximity of the biomass probe to vessel walls, pO2 probe and sparger with the bubbles from aeration having a significant effect on the signal. The three prediction models were a high cell density suspension serially diluted to a low cell density, real time culture suspension data and combination of the high cell density and real time data. From the prediction models, capacitance versus viable cell density at the dual frequency of 0.2 and 10 MHz at 30 °C showed best predictions with error of all three models between 0.26 - 0.36 × 106 cells/ml. All models for viable cell volume were accurate at the lower ranges, with error increasing as the viable cell volume increased. Combination of high cell density suspension and real time data allowed the best cell volume predictions at 37 °C with errors of 1.1 – 1.2 x 109 μm3 ml-1. Optical density and an automated cell counter were also investigated for the estimation of viable cell density and were found to be not as accurate as the capacitance prediction of viable cell density.