We set out to study how the 'promise of green 5G' is produced and circulated. We conducted an analysis of a UK-focused corpus of documents that represent key sites through which the promise of green 5G is produced, circulated and challenged. By the promise of green 5G we refer to an emerging, overarching, dominant expectation that 5G will produce positive environmental sustainability benefits of various kinds. We employed an analytical approach informed by the sociology of expectations and the concept of technoscientific promises. We asked: what are the particular contents of this promise (i.e. the more specific promises and expectations it is built upon), how do ‘enactors’ seek to boost its legitimacy and credibility, what activities are involved in its production and circulation and what are its present-day material effects, does the promise exclude or overlook alternative options, and is it challenged? We pursued these aims and questions through a document analysis of a diverse corpus (n=260) comprised of UK newspaper articles and newswire results, and reports and webpage content from industry, standardisation bodies and research consortia.