The IAEA-386 bovine liver candidate reference material is prepared specially for micro-analytical techniques. The development process including material collection, drying, pulverizing, sieving, homogenization and preliminary test is described in detail. More effective grinding methods were established to achieve the median partiele size of 22 μm. For reasons of quality control and better assessment of resulting data, its certification campaigns on world-wide will be organized by the IAEA.