Funding: Authors acknowledge the funding from UKRI Future Leaders Fellowship (MR/W007460/1). A.M. thanks the University of St Andrews (Impact & Innovation Fund) for funding. M.T. and J.C.T. thank the ERC Consolidator Grant (PROMOFS grant agreement 771575) for funding the research. ABN gratefully acknowledges funding from the EPSRC through grant numbers EP/L017008/1, EP/R023751/1 and EP/T019298/1. We report here the synthesis of polyureas from the dehydrogenative coupling of diamines and diformamides. The reaction is catalysed by a manganese pincer complex and releases H2 gas as the only by-product making the process atom-economic and sustainable. The reported method is greener in comparison to the current state-of-the-art production routes that involve diisocyanate and phosgene feedstock. We also report here the physical, morphological, and mechanical properties of synthesized polyureas. Based on our mechanistic studies, we suggest that the reaction proceeds via isocyanate intermediates formed by the manganese catalysed dehydrogenation of formamides. Publisher PDF