Most analytical techniques used for the speciation analysis of butyltin compounds in biological tissues usually contain multiple procedures (e.g., extraction, derivatization, separation, preconcentration, determination) which may increase the risk of systematic errors. The use of reference materials (RM) makes it possible to correct most of these errors and improve the validity of quality control. In this study, a new candidate RM for butyltin compounds in mollusks was developed. It was prepared with a mollusk ‘Mya arenaria’ directly bought from the market. The preparation of this candidate RM, the homogeneity and stability studies, the value assignment and the evaluation of uncertainty were described. The certified values of 0.33 ± 0.08, 0.62 ± 0.09, 2.64 ± 0.20 μg Sn g−1 (based on dry mass) for monobutyltin (MBT, [Sn(C4H9)3+]), dibutyltin (DBT, [Sn(C4H9)22+]) and tributyltin (TBT, [Sn(C4H9)3+]) respectively have been assigned by inter-laboratory comparison. This work will be of great support to the monitoring of butyltin compounds in biota, as well as meeting the need for implementing international treaties in China.