Background: Due to increasing environmental issues, the social marketing efforts from organisations are increasing with the aim to push for more sustainable behaviour. One recurring issue in these campaigns is palm oil production. Generally, social marketing relies on negative emotional appeals, such as fear, shame, and guilt, to generate desired responses to the message. This paper focuses on the use of both positive and negative emotional appeals in social marketing within the area of environmental sustainability.   Purpose: The purpose of this study is to examine the relationships between the elements of the theory of planned behaviour with the addition of the social marketing appeal and how it, in turn, affects the intention to avoid palm oil. Further, the research aims to study the effects of positive emotional appeals within pro-environmental social marketing.   Method: To conduct this study, a quantitative approach was taken. Two questionnaires were made with the aim to measure respondents’ motivational factors leading to an intention to behavioural change based on the marketing appeal. One questionnaire included an advertisement using a positive appeal whereas the other utilised a negative appeal.   Conclusion: Both marketing appeals show positive relationships between the elements in the adapted theoretical framework, with perceived behavioural control being the strongest predictor of the intention to behavioural change. Further, it was discovered that the financial factor can be important to consider when it comes to sustainable consumption.