Since the 1990s, the number of websites and web users, especially older users, has increased extensively. Despite the rapid growth in the number of websites, a significant number of ergonomic violations still hinder the information search activity performed by web users. As ageing is associated with reduced working memory capacity, inhibition failure, slowing of processing speed and more generally impaired executive functioning, older adult web users may experience difficulties while searching for information, especially when the website includes ergonomic violations, such as usability and accessibility violations. In this experiment, the navigation activities of younger and older web users were compared while they were searching for information on a website that met ergonomic guidelines and on a website that included ergonomic violations. The participants then performed a free, delayed-recall task to assess their mental representation of the website they had just navigated. The main findings showed that ageing had a negative impact on search performance but few effects on mental representation built by participants. On the contrary, the ergonomic quality of the website had an impact on search performance and mental representation built by the participants.