Negative persuasive attacks and misinformation are major threats to public support of governmental mandates. Here, we introduce and investigate the treatment heterogeneity of the trust inoculation, first of a new kind of sociopsychological inoculation designed around the social dimensions of persuasion to protect against negative persuasive attacks and misinformation. In two preregistered studies, we provide evidence that inoculating citizens about the trustworthiness of key energy stakeholders moderately protected citizens’ support for a renewable energy part of national energy transitions to net-zero emissions, against multiple negative persuasive attacks, in Switzerland (N=389) and in seven European countries (N=2805). Baseline trust in energy stakeholders did not moderate the effects, but the trust inoculation protected the citizens most susceptible to negative persuasive attacks. Our findings demonstrate that sociopsychological inoculations such as the trust inoculation are promising, easily implementable and scalable interventions to protect governmental mandates from multiple negative persuasive attacks and misinformation.