Social isolation is a problem that is accentuated in the stage of old age. This condition puts the physical and mental integrity of older adults at risk. This paper presents a predictive model for the automatic detection of social isolation in older adults. The predictive model was implemented in a mobile application that monitors communication and mobility activities performed by an older adult. The mobile application was also generated for a caregiver who is responsible for receiving notifications about the specific level of social isolation of the older adult. The predictive model was evaluated using an experimental group of older adults.