A reliable and rapid speciation method for the determination of both butyl- and phenyltin compounds in environmental samples has been developed. Organotins are extracted from solid matrices by acid leaching. The analytical procedure is based on the one-step simultaneous ethylation/extraction using the reaction with sodium tetraethylborate in aqueous phase in the presence of isooctane. Direct analysis of the organic layer is performed using gas chromatography interfaced to Flame Photometric Detection (GC-FPD). Absolute detection limits of a few pg tin are reached. The technique has been validated by its application to different polluted environmental samples: wastewaters, sediments and biological tissues from marine and freshwater environments and intercomparisons on freshwater sediment and a mussel sample.