Purpose: Environmental disasters have caused various human, ecological, and economic damage worldwide. To reduce the potential damage and save lives in the short term, the volunteers are involved in support in disaster situations. Given this scenario, studies on volunteers who work in disaster contexts in Brazil proved to be an interesting and necessary research topic. Design/methodology/approach: This research employed a qualitative methodology, utilizing 16 semi-structured, in-depth interviews to gather data. The process of selecting participants was carried out through the snowball sampling technique, focusing on individuals volunteering in disaster response within the Brazilian setting. Following data collection, a thorough content analysis was undertaken. The motivations uncovered through this analysis were then meticulously compared and contrasted against the Volunteer Functions Inventory (VFI), which is rooted in the psychological functionalist theory of volunteerism. Findings: The findings of this study advance the literature by confirming four motivations for volunteers to act in disasters, as identified in the VFI: values, enhancement, protective, and social. Additionally, this study contributes by bringing to light two new motivations, knowledge, and readiness, which emerged from the content data analysis. The study also advances by clustering the behavior profiles determined from these motivations as expert, sensitive, altruistic, beginner, and social. Originality/value: Based on the results, a Disaster Volunteer Framework was proposed, which serves as a basis for developing public policies for the government and assists institutions that work in disaster management in attracting new volunteers.