The new partially organylsubstituted polycyclophosphanes P7Pri4H, iso-P7Pri4H, P8Pri5H, P9Pri4H, and P10Pri5H have been obtained by reaction of PriPCl2 with PCl3 and magnesium and subsequent chromatographic work-up of the crude reaction product containing isopro-pylphosphorus magnesium compounds. According to 31P NMR spectroscopic investigations, P7Pri4H is 7-hydrogen-2,3,5,6-tetraisopropylbicyclo[2.2.1]heptaphosphane, iso-P7Pri4H is hydrogen tetraisopropylbicyclo[2.2.1]heptaphosphane, P8Pri5H is hydrogen pentaisopropylbicyclo[3.3.0]octaphosphane (two constitutional isomers), P9Pri4H is hydrogen tetraisopropyltricyclo[3.3.1.03,7]nonaphosphane (two configurational isomers), and P10Pri5H is 10-hydrogen-3,4,5,8,9-pentaisopropyltricyclo[5.2.1.02,6]decaphosphane (two configurational isomers).