A new environmental certified reference material (CRM) has been developed by the National Institute for Environmental Studies (NIES) to support research and development studies on trace heavy metals in landfill cover soils. The method of analysis requires the use of a 1 mol per L HCl solution to extract the metals of interest, the procedure being based on an official test method (Notification Method No. 19) of the Ministry of the Environment, Japan. Certified values for element concentrations have been issued for Al, Cd, Cr, Co, Cu, Pb, Mn, Ni, V and Zn, while reference values have been assigned to As, Fe and Hg. The efficiency of extraction for elements of interest was investigated using standard solutions of HCl (0.01, 0.1, 0.5, and 1 mol L⁻¹) and ultrapure water (UPW) and wide variation in extraction efficiency was noted reflecting the importance of chemical speciation in the context of liberation of analytes from the host matrix. The extractability of Cd, Cu, Mn, and Pb was relatively high (over 50% relative to the total metal content) for acid strengths in the range 0.1 to 1.0 mol L⁻¹, in contrast to that of Hg where the extraction efficiency was less than 5% even in 0.5 mol L⁻¹. On the basis of submitted data, the CRM is considered appropriate for use in analytical quality control for element speciation and trace analysis as well as for evaluation of new or modified extraction procedures based on the official test method.