The study of three marine sediments is the first in a series of reference samples to be developed for characterizing the bottom sediments of the Pacific Ocean and the Red Sea. The three samples were certified for their contents of major, minor and some trace elements. These values were assigned on the basis of statistical processing of the data obtained from an interlaboratory experiment conducted with the use of physical, physico‐chemical and chemical methods of analysis. The Soviet, Czechoslovakian and Bulgarian laboratories took part in the interlaboratory experimen