mono(phosphorus ligand)palladium(0) complexes catalyzed alkene insertions into hydrogen–tungsten bonds. These insertions using WHCp(CO)3 with ethyl acrylate and dimethyl fumarate smoothly gave the corresponding alkyltungsten complexes. Kinetic studies involving the stoichiometric reactions and DFT calculations suggest the following steps: (i) formation of a mono(phosphorus ligand)mono(alkene)palladium(0) species