Open spaces in cities, such as green spaces and parks, are key elements of urban landscapes and urban sustain ability. Open spaces improve the quality of the environment, quality of life, and promote social interaction and inclusion. There is evidence of positive impacts on health. This research analyses the potential accessibility to open spaces in two Chilean cities, Valdivia and Temuco. Analysis of accessibility is based on patterns of daily mobility by travelers while considering their trips and transport modes, in particular walking. Statistical analysis of trip length forms the basis of an adaptive threshold for the calculation of a cumulative potential measure of accessibility. The analysis shows that, for these two cities, variations in accessibility tend to be driven by age and gender, and less by income. There are also variations between the two cities, with Temuco showing better levels of accessibility, as a consequence of residents generally undertaking longer walking trips. (C) 2016 Elsevier Ltd. All rights reserved.