Abstract:To achieve product differentiation, airlines spend millions of dollars annually in signing celebrities to endorse their brands’ endorsement contracts, as source effects that play an important role in persuasive communications. Based on source credibility theory and product differentiation theory, this study examines the causal relationship between endorser credibility, brand attitude, brand credibility and purchase intention of air transportation services provided by airlines that adopt a celebrity endorsement strategy. Meanwhile, endorser credibility was tested as a second-order construct of the proposed model. The results indicate that positive relationships exist between all the hypothesized constructs. Therefore, in addition to having a favorable celebrity to endorse a customer oriented advertisement, the credibility of the celebrity is as important in enhancing brand attitude, brand credibility and purchase intention.