To reduce human dependency on fossil fuels, increasing attempts are being made to substitute synthetic materials in products with bio-based materials. Global brands attempt to differentiate themselves by adding bio-based materials to their products. However, little is known about consumers' reactions regarding brands that use bio-based materials. Two experimental studies in six European countries on bio-based products were used to test whether consumers responded differently to brands that use materials that are fully bio-based (i.e., 100% bio-based) compared to brands that use materials that are partially bio-based. The results provide evidence that only brands with attributes that were 100% bio-based consistently resulted in enhanced purchase intentions. Instead, introducing partially bio-based attributes does not always result in a better evaluation of the brand compared to brands that do not contain any bio-based attributes. Additionally, the authors show how these effects occur (i.e., via brand attitude and brand emotions) and under which conditions these effects are enforced (i.e., environmentally conscious consumers and private labels). Finally, these effects are seen for multiple products, brands and countries. The study offers theoretical and practical implications and presents avenues for future research.