In an attempt to determine if poorly designed user interfaces (UI) can impact the emotions of the user, this study set out to answer the question “What effect does a poorly designed user interface have on its users’ emotions?”Thus, a survey of previous literature in the fields of UI/UX, usability and emotional psychology was conducted for an overview of existing knowledge, and necessary information for conducting appropriate tests for this study.The authors then created a user interface prototype that deliberately disregarded or broke UI/UX best practices and standards, for controlled variables to be tested in the following user tests. Participants of the user tests were asked to complete a certain task using the UI, during which the observers noted pain points in the process and apparent emotional reactions to discuss in the following qualitative, semi structured interview where the participants were asked to elaborate on their experiences.The findings from the tests and interviews were compiled and put through inductive thematic analysis, allowing the authors to make conclusions and answer the research questions. Every participant of the tests and interviews reported at least one significant negative emotional reaction during the completion of the task. A wide range of different emotions were reported, such as stress, disappointment, distrust and confusion, but most commonly was frustration and other emotions on the spectrum of rage such as irritation, annoyance and even anger. The majority of participants noted that, if it were a real site, they would have exited before completing the desired task. They also showed to build a negative perception of the brand or company (in this case the airline) responsible for the site, with their negative emotional connotations towards the interface transferring to the owner of the website.It was concluded that a poorly designed user interface will cause negative emotional reactions in its users, most likely some form of anger or frustration. This impacts both the user, but also the organization running the site, as bounce rates increase and their public perception worsens.