Most of usability evaluation methods for the Web domain have several limitations such as: the concept of usability is only partially supported; usability evaluations are mainly performed when the Web application has been completed; there is a lack of guidelines on how to properly integrate usability into Web development. This paper addresses these issues through the presentation of a Web Usability Evaluation Process (WUEP) for integrating usability evaluations at different stages of model-driven Web development processes. A case study was performed in order to analyze the feasibility of the approach by applying WUEP to evaluate the usability of a real Web application that was developed by using a specific model-driven development process in the industrial domain. The results suggest that WUEP provides good insights into the performance of usability evaluations. The usability problems are corrected at the model and model-transformation levels, thereby improving the usability of the final Web application.