Abstract Reactions of esters of formic acid, HCOOR (R=C2H5, CH2C6H5), with Ni(0)-complexes (mixtures of bis(1,5-cyclooctadiene)nickel (Ni(cod)2) and tertiary phosphines (PR′3)) lead to decarbonylation of HCOOR to afford (Ni(CO)n (PR″3)4−n and ROH. Vinyl formate gives a mixture of CH3CHO, Ni(CO)n(PR′3)4−n, C2H4, and CO2 on interaction with the Ni(0)-complexes. β-Lactones liberate CO2 on treatment with the Ni(0)-complexes. Oxidative addition of the reactants to Ni involving cleavage of the C–O bond(s) accounts for the formation of the products.