Older adults encounter numerous barriers to mobility, many of which are in the built environment. Technological solutions may enable them to mitigate these barriers and promote physical activity. To design appropriate technological solutions, it is crucial to understand the specific barriers to mobility older adults face from their perspectives. Photo diary studies allow older adults to autonomously document their experiences to support generation of user needs and requirements. We investigate the methodological appropriateness of photo diaries for exploring experiences of older adults and eliciting their requirements for new technologies. A photo diary study was conducted with 26 older adults, who were given disposable cameras to document things that affect their mobility. As well as presenting a selection of the mobility barriers identified in this study, the paper outlines a number of methodological issues relating to the use of photo diaries for eliciting the needs and requirements of older adults.