The aim of the research described in this publication is two-fold. The first is a detailed description of the synthesis of a series of compounds containing a stereogenic heteroatom, namely the optically activeP-stereogenic derivatives oftert-butylarylphoshinic acids bearing sulfur or selenium. The second is a detailed discussion dedicated to the determination of their structures by an X-ray analysis. Such a determination is needed when considering optically active hetero-oxophosphoric acids as new chiral solvating agents, precursors of new chiral ionic liquids, or ligands in complexes serving as novel organometallic catalysts.