Abstract Communication skill and trust are regarded as two important obstacles in food safety risk communication. Prior researches found certainty claim cannot always lead to positive communication effectiveness. Trust plays an important moderation role between this relationship. Through two studies we tested our hypotheses. In study 1, we found that under high expertise-trust condition, the relationship between certainty claim and communication effectiveness shows as an inverted-U shape; under high benevolence-trust condition, certainty claim positively influences communication effectiveness; neither under low expertise-trust or low benevolence-trust conditions, there is no significant relationship between certainty claim and communication effectiveness.
