2-(2-Pyridyl)benzo[ b]selenophene has been investigated as a possible reagent for palladium. From a consideration of its reactions with diverse metal ions, and the probable structure of the complex formed between the compound and palladium(II) it is postulated that the group ▪ may be highly selective for palladium. From the experimental evidence it is suggested that the delocalization of the metal electron density by π-bond formation between the palladium and selenium atoms is a major factor in determining the stability of the chelated complex.