To evaluate the psychometric properties of different factorial models of the Medical Outcomes Study Social Support Survey (MOS-SSS) and screen the frequency of social support in older Brazilians. Methodological study. Five factorial models of the MOS-SSS were tested for their validity and reliability using three Brazilian samples from different locations in the country. The factorial invariance was assessed across locations using multigroup analysis. The global average score was calculated. A total of 1574 older people participated in the study. For all models, there was adequate factorial and convergent validity and good reliability; the discriminant validity was not achieved. Therefore, a second-order hierarchical model was proposed and showed validity, reliability and invariance across samples. In the three Brazilian samples, participants presented high frequency of social support. A second-order hierarchical model was fitted the Brazilian samples, allowing the calculation of the global score of social support, which was high among the participants. The MOS-SSS assesses social support levels among older individuals in community or clinical settings. Nurses can tailor interventions based on scale outcomes for personalised care for older people.