Within the framework of process analytical technology, infrared spectroscopy (IR) has been used for characterization of biopharmaceutical production processes. Although noninvasive attenuated total reflection (ATR) spectroscopy can be regarded as gold standard within IR-based process analytics, simpler and more cost-effective mid-infrared (MIR) instruments might improve acceptability of this technique for high-level monitoring of small scale experiments as well as for academia where financial restraints impede the use of costly equipment. A simple and straightforward at-line mid-IR instrument was used to monitor cell viability parameters, activity of lactate dehydrogenase (LDH), amount of secreted antibody, and concentration of glutamate and lactate in a Chinese hamster ovary cell culture process, applying multivariate prediction models, including only 25-28 calibration samples per model. Glutamate amount could be predicted with high accuracy (R-2 0.91 for independent test-set) while antibody concentration achieved good prediction for concentrations >0.4 mg L-1. Prediction of LDH activity was accurate except for the low activity regime. The model for lactate monitoring was only moderately good and requires improvements. Relative cell viability between 20 and 95% could be predicted with low error (8.82%) in comparison to reference methods. An initial model for determining the number of nonviable cells displayed only acceptable accuracy and requires further improvement. In contrast, monitoring of viable cell number showed better accuracy than previously published ATR-based results. These results prove the principal suitability of less sophisticated MIR instruments to monitor multiple parameters in biopharmaceutical production with relatively low investments and rather fast calibration procedures. (c) 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:578-584, 2015