A review of tomography systems suitable for industrial implementation and design considerations for tomographic sensors has allowed the design of an ERT sensor compatible with stringent process requirements. In conjunction with a data acquisition system, ITS P2000, this sensor was applied to processes considered typical of Active Pharmaceutical Ingredients (API) chemical development. Experimental results are described where variations in conductivity measurements were monitored in a stirred tank. The data were compared with spectroscopic on-line monitoring and kinetic information. The results obtained demonstrate that this approach shows promise for on-line control of mixing process performance and efficiency evaluation and optimisation of reactor geometries.