Abstract Flexible electronics is an emerging thin film based technology enabling completely new types of products and applications compared to conventional electronics. Since the quality of films defines the functionality of fabricated devices, the lack of suitable online manufacturing quality assessment tools has been identified to be a critical bottleneck while upscaling the volume and the yield of thin film electronics manufacturing. In order to solve that problem, a synchronized thermography (ST) based online measurement system was built. Applicability of proposed roll-to-roll compatible ST based system was demonstrated by characterizing a moving plastic film with conductive indium tin oxide on top. Obtained results show that ST can be utilized for online homogeneity characterization and sheet resistance estimation of large area thin films which are not possible with other existing methods.