Abstract. This article analyses whether different institutional sources of scientific information have an impact on its credibility. Through a population-based survey experiment of a national representative sample of the Spanish public, we measure the credibility that citizens attribute to scientific information on the evolution of CO₂ emissions disclosed by different institutional sources (business associations, government, non-government environmental organisations, international bodies and national research institutions). The findings show that an institutional credibility gap exists in science communication. We also investigate the factors accounting for the credibility of the different institutional sources by examining variables related to knowledge, interest, trust, reputation, deference, attitudes, values and personal characteristics. Exploratory regression analyses reveal that identical variables can produce different effects on the credibility of scientific information, depending on the institutional source to which it is attributed.