Selenium (Se) is an essential element to animals and humans. Intake of Se originates primarily from consumption of Se-enriched crops and vegetation growing in Se-rich soils, which originated, in most cases, from Se-rich parent materials (rocks). An accurate measurement of the concentration and speciation of Se in Se-rich rocks and soils is therefore necessary and depends strongly on the type and origin of Se-rich rocks and soils. In this paper, we present results from preparation and certification of four reference materials for Se-rich rocks, and five for Se-rich soils.