Background: A time-geographic diary approach is of interest in occupational therapy due to the inclusion of the diarist’s subjective experiences. There are several methods for detecting doing in time, but details needed for analysis are still lacking. The smartphone application POrtable Diary Data collector (PODD), a 24-hr diary based on the time-geographic diary has recently been introduced. Aim: To test the usability of PODD as a tool for diary data collection to detect and visualize sequences of daily activities. Material and methods: An exploratory sequential design was used, where diary data was first collected and then followed by a questionnaire assessing usefulness. Thirty-one occupational therapy students participated. Usability testing was applied, exploring how participants experienced the use of the device. Data was analysed qualitatively and quantitatively. Results: The PODD visually presents activity sequences and thus assists in detecting patterns of daily occupations (PDO). The students agreed on the supportive statements concerning learnability, efficiency and memorability. Regarding errors and satisfaction, participants agreed that the device was easy to use. Conclusions: Using a mobile application to collect data about students’ daily activities was effective. However, the PODD needs to be further evaluated among other groups and contexts as well as for its usefulness for PDO analyses.