This article seeks to analyse the migration trajectory from commercial off-the-shelf and closed source software to open source software in order to establish the critical success/resistance factors associated with the replacement of the extant Microsoft Office with Open Office software in a private Brazilian company. The bibliographical review of this work addresses adoption/resistance to information systems, which is the theoretical framework adopted to explain the data collected. The single case study method was then applied and data was collected via documentation analysis, interviews, questionnaires, and direct and participant observation. Data analysis was then conducted by means of content analysis and non-parametric statistics. Based on that, three types of user behaviour were identified with respect to the intention to use open source software, namely adopters, partial adopters, and non-adopters. Finally, the reasons for such behaviour were set forth and discussed in order to make the implications of the study clear. © 2017 Elsevier Inc.