Methods are described for the determination of the total organotin compounds by atomic-absorption spectrophotometry and for the specific determination of bis(tri-n-butyltin) oxide and di-n-butyltin oxide by atomic-absorption spectrophotometry and polarography. Bis(tri-n-butyltin) oxide and di-n-butyltin oxide are extracted from the wood with hydrochloric acid-ethanol solution and separated from each other and from wood extractives, fungicides and insecticides by adsorption on to Amberlite CG-120 cation-exchange resin followed by elution with solutions containing different concentrations of hydrochloric acid in ethanol. The procedures have been used to determine bis(tri-n-butyltin) oxide and di-n-butyltin oxide in Scots pine, Corsican pine, Western hemlock, Japanese larch, Sitka spruce, Douglas fir and Western red cedar.