Three improved thiophosphoroselenenylation procedures of CH-acids, including derivatives of malonic and acetyl-, phosphono-, 4-nitrophenyl- and 3-pyridylacetic acids, have been described and compared to previously reported thiophosphoroselenylation of di-Et malonate using bis(disopropoxyphosphinothioyl)diselenide alone or with the aid of Me iodide. The use of iodine makes it possible to utilize both equivalent of the selenenylating agent. The procedures work well for the majority of nucleophiles in a pKa range between more acidic malononitrile or Meldrum acid and less acidic phenylacetates. The reaction carried out on di-Et malonate in boiling rectified ethanol yields selenoacetate, which cannot be obtained by direct phosphoroselenenylation. Crystal structure of one of the selenomalonamides confirms the stabilization effects of both carbonyl oxygens on selenium atom. The P-Se bond splitting, using TBAF in 3-M excess in the presence of alkylating agent yields the resp. C,Se-dialkyl derivatives