A simple and reliable extraction method was developed for quantitative determination of both butyl- and phenyltin compounds in sediments by capillary gas chromatography combined with inductively coupled plasma mass spectrometry (GC-ICP-MS). Both types of organotin compounds were extracted quantitatively from sediment by mechanical shaking into tropolone–toluene and HCl–methanol. After phase separation and pH adjustment, these organotins were ethylated with sodium tetraethylborate. The method was evaluated by analyzing PACS-2 and NIES No.12 sediment certified reference materials. The dibutyltin (DBT; 1.14 ± 0.02 μg g⁻¹) and tributyltin (TBT; 1.01 ± 0.04 μg g⁻¹) values observed in PACS-2 sediment closely matched the certified values (DBT, 1.09 ± 0.15; TBT, 0.98 ± 0.13 μg g⁻¹ as tin). The monobutyltin (MBT) value was higher (0.62 ± 0.02 μg g⁻¹) by more than two fold over the reference value (0.3 μg g⁻¹ as tin). The concentrations of TBT (0.18 ± 0.04 μg g⁻¹) and triphenyltin (TPhT; 0.0099 ± 0.002 μg g⁻¹) in the NIES No.12 sediment were also in good agreement with the certified and reference values of TBT (0.19 ± 0.03 μg g⁻¹ as compound) and TPhT (0.008 μg g⁻¹ as compound), respectively. Recoveries of TBT, tripentyltin (TPeT) and TPhT from spiked sediments were satisfactory (TBT, 102 ± 3.4%; TPrT, 96 ± 3.4%; TPhT, 99 ± 8.5%). The detection limits as tin were in the range 0.23–0.48 ng g⁻¹ for a 0.5 g sample size. It is also noteworthy that clean-up of the extract is not necessary because of the superior selectivity of ICP-MS detection. The present method was successfully applied to marine sediment samples.