Background: Studies conducted have shown that half of the South African population uses either or both Facebook and Twitter social networking sites for social satisfaction and for the evaluation of products and purchase decisions. This is a direct result of the continuous technological advancements worldwide and the permeative nature of social media. Objective: The focus of this study is to evaluate the credibility of Facebook and Twitter messages while establishing which of the mediums is perceived as more believable by consumers. The results of this research direct information technology practitioners, business managers, business owners, and marketing managers on the viability of these communication mediums. Method: A positivistic paradigm was used in this study through the use of a descriptive research design which consisted of a survey of 446 respondents located in East London, Eastern Cape Province of South Africa. Respondents were either selected randomly or through convenience sampling and were between age 18 and 55. Results: It was established that both Facebook and Twitter are significantly related to the independent variable of ‘intention to purchase’, with Twitter having a stronger correlation with the independent variable than Facebook. The context of the study was set in relation to the purchase intention of specific mobile phone brands. Conclusion: Based on these results, it can be concluded that Twitter electronic word-of-mouth can be considered to be more credible than Facebook electronic word-of-mouth; thus this should be considered when advertising or promoting products via these mediums.