Epitaxial layers of ruthenium-doped InP grown by low-pressure hydride vapor phase epitaxy have been studied. Current voltage measurements were conducted at temperatures between 20 and 200 degreesC for samples doped with Ru in the range 1 x 10(17) to 5 X 10(17) cm(-3). In this doping range, the specific resistivity of n(+)/InP:Ru/n(+) structures accommodating electron injection is less than or equal to1 x 10(4) Ohm cm and that of p(+)/InP:Ru/p(+) structures accommodating hole injection is as high as 3 x 10(10) Ohm cm. The reason for such a huge difference in the resistivity of these structures is attributed to a low activation of deep Ru acceptors, thus rather giving rise to an n(-) layer than a semi-insulating layer, as supported by our theoretical simulation. Analysis of the Arrhenius plots constructed from the temperature-dependent I-V curves yield an average activation energy of Ru with reference to the conduction band equal to 0.44 and 0.52 eV under electron and hole injection, respectively.