There is a complex relationship among social media use by non-profit organizations and online social capital, credibility of information and humanitarian crises, particularly with regard to the increasing proliferation and strength of social media on a global scale, including Yemen. Due to the need to expand studies in the Yemen due to humanitarian crisis especially in the last few years, this study empirically investigates such a relationship through the use of one model based on the literature related to the impact of social media use on social capital online and humanitarian crisis response, the relationship between social capital online and its influence on humanitarian crises response, the mediating influence of social capital online on the relationship between social media use and humanitarian crises response, and moderating influence of information credibility on the relationship between social media use and social capital online. The study employed a quantitative method to obtain the data of the study, using a survey questionnaire which was distributed to 423 non-profit organizations in Yemen. In this study, a simple random sampling was applied for selecting the organizations from the list which was obtained from the study of civil society organizations in Hadramout conducted by the Ministry of Social Affairs in Yemen. The data was analyzed with SPSS 22 to test normality. Besides, each individual construct was tested using AMOS version 6 to assess the measurement model for exogenous and endogenous variables. The findings reveal that the hypothesized relationships were generally supported, specifically the social media which was found to significantly affect the social capital online during humanitarian crises. Moreover, it was revealed that the access to information, knowledge sharing and interactive participation were important in terms of their effects on the creation of social capital online. The results also showed that credibility of information improved the social media use-social capital online relationship. The study has several implications among which the non-profit organizations can guarantee a long-term successful social relationship with community and humanitarian crises victims in terms of the social media growth. The study recommends that future studies can corroborate the findings by investigating the relationship between motivations towards social media use and new technologies use for sharing information, and how the needs are met by the same, in the case of natural crises in Yemen.