The amount of e-commerce websites has increased rapidly. However, issues involving their usability many tomes have been overlooked. This research is concerned about the inefficiency of the presentation of products in general, in ecommerce websites at the moment of purchase. This incompetence jeopardizes the accomplishment of the task by the user, who will become frustrated and unsatisfied not to mention the economic losses. It is intended, with the research, to improve the usability of the e-commerce websites through the identification of factors that will enable the user to select better his products at the moment of purchase. Moreover, it is intended to contribute to the development of solutions of usability issues and to improve the studies of IHC. Some methods and techniques were used, in four stages: First of all, through the Task Analysis, we could observe the clients actions at the very moment of selection of two products from the real store; Secondly, through the Heuristic Evaluation, we tried to study the interface of the domestic appliance websites selected for a survey from the Task Analysis; On a third stage, through the Cooperative Evaluation, we analyzed the process of selection of the same products mentioned above by the clients on virtual store; At last, the actions of the users were both analyzed and compared in the virtual store and the real store, in order to verify the differences between them at the moment of the products selection. By means of this work, the hypothesis could be confirmed and became evident that the interfaces of the e-commerce websites showed low levels of usability, risking the performance of task by the users besides leading the user to frustration and most of the time making him give up the purchase.