The rare earth monophosphides LnP ( Ln = La, Nd Sm, and Y) have been prepared. Their electrical properties have been studied. The compounds exhibit a lower resistivity and higher carrier concentration. Evidence that shows semiconducting properties has been obtained from the study of energy gaps and the negative temperature coefficient of resistance. Their energy gaps are in the range of 1.0-1.46 eV. The electrical properties of LnP can be reasonably well explained by the proposed band scheme.