Low-carbon technologies are necessary to combat global warming. However, they are often opposed by members of the general public, causing costly delays and cancellations. In this article, I argue that language may be a relevant cause of such opposition. I introduce a theoretical model describing a boomerang effect in which positively framed communication about low-carbon technologies may actually lead to opposition in the long run. An example of positive framing is emphasising the climate benefits of a technology while neglecting to mention associated safety risks. I predict that, over time, people begin to perceive positive framing as an attempt to manipulate them into supporting a technology. In turn, this perceived manipulation may make them feel that their freedom to make their own decision to support or oppose the technology is under threat. To counter this behavioural threat, people may begin to oppose low-carbon technologies. My boomerang model further describes how certain characteristics of the source of information as well as of the recipient may influence both the direct and indirect effects of positive framing. I then discuss the model’s implications for effective communication and indicate directions for future research.