Advances in genetic engineering have improved specificity, safety and potency of T-cell receptor (TCR) and Chimeric Antigen Receptor (CAR-T) based therapies for solid and non-solid tumours. These developments have allowed the manufacturing and commercialisation of these immunotherapy ATPMs (advanced therapy medicinal products). However, there is a current need to develop more robust product release assays to shorten product release time, including methods to ensure the identity, safety or potency of the product. Current methodologies to evaluate product potency require cell labelling, are labour intensive and only provide information about product’s specific cytotoxic effect at one selected time-point. The xCELLigence platform overcomes these limitations by measuring electrical impedance over time. In this presentation we will discuss how to develop and qualify the use of a high-throughput impedance-based system to measure T-cell cytotoxicity for both TCR or CAR-T approaches using either suspension or adherent target cell lines.