An investigation is made of the absorption spectra of triplet metastable helium molecules in the a(3) Sigma (+)(u)state in liquid He-4 and He-3 at various pressures and in dense He-3 gas. An analysis of the spectrum corresponding to the a(3)Sigma (+)(u) --> c(3)Sigma (+)(g) transition confirms the conclusion that there is a microscopic bubble surrounding the molecule in liquid helium. A simple approximation is proposed for the wave function of the valence electron of the molecule and the parameters of the bubble are determined for various experimental conditions. The coefficient of molecular recombination in liquid He-3 and He-4 was determined experimentally at various pressures and in dense cold He-3 gas. The results show good agreement with the theory of mutual recombination limited by molecular diffusion under conditions of strong van der Waals interaction. It is shown that in the condensed phases of helium the polarization of the molecules under the action of the magnetic field does not lead to suppression of their mutual recombination, and this is confirmed experimentally. (C) 2000 MAIK "Nauka/Interperiodica".