Against this backdrop, we hypothesized that a π-bound olefin could be used as an element of ligand design for H2 activation. Since the discovery of non-classical H2 complexes by Kubas, knowing whether they can transfer hydrogen atoms to unsaturated substrates without prior H-H cleavage has been a long-standing question. Supporting evidence came, amongst other, from kinetic studies on olefin hydrogenation involving a diruthenium-H2 intermediate and parahydrogen induced polarization (PHIP) experiments on photoinduced hydrogenation mediated by transient [Mo(CO)3(H2)(olefin). A few examples of metal complexes bearing a PC=CP pincer ligands have been reported; one example undergoing reversible interconversion between an olefin metal hydride and the corresponding metal-alkyl formed by b-insertion, showing that hydride migration can occur between ligands occupying trans positions. The fact that alkyl complexes of 3d metals such as Ni(II) are often thermodynamically resistant to b-hydride elimination further suggested that hydride transfer to a bound olefin could provide the much-needed driving force for cooperative H2 activation. Additionally, the hydricity of the resulting Ni-H bond may be enhanced by the trans alkyl carbon. Therefore, we set out to investigate the ability of Ni(0) complexes of PC=CP pincer ligands to activate and transfer H2. In this report, we show that the incorporation of a precoordinated olefin in a pincer ligand framework allows for the observation of both a non-classical Ni-(H2) intermediate and the corresponding alkyl(hydrido) activation product, both in rapid equilibrium with dissolved H2. Experiments and DFT calculations support a direct ligand-to-ligand hydrogen transfer (LLHT) mechanism without a dihydride intermediate. The catalytic relevance of this cooperative mechanism is demonstrated in the selective semihydrogenation of diphenylacetylene to Z- stilbene under mild conditions, with a comparable performance to recently disclosed Ni-based systems.