The isochoric thermal conductivity of solid nitrogen has been investigated on four samples of different densities in the temperature interval from 20 K to the onset of melting. In <$E alpha - roman N sub 2> the isochoric thermal conductivity exhibits a dependence weaker than <$E LAMBDA~symbol Х~1 "/" T>; in <$E beta - roman N sub 2> it increases slightly with temperature. The experimental results are discussed within a model in which the heat is transported by low-frequency phonons or by "diffusive" modes above the mobility edge. The growth of the thermal conductivity in <$E beta - roman N sub 2> is attributed to the decreasing "rotational" component of the total thermal resistance, which occurs as the rotational correlations between the neighboring molecules become weaker.The isochoric thermal conductivity of solid n-hexane C6H14 has been investigated on three samples of different density in the temperature interval from 100 К to the onset of melting. In all the cases the isochoric thermal conductivity varied following a dependence which is weaker than <$E LAMBDA~symbol Х~1 "/" T>. The results obtained are compared with the thermal conductivities of other representatives of n-alkanes. The contributions of low-frequency phonons and "diffuse modes" to the thermal conductivity are calculated.Thermal conductivity of solid furan has been measured at isochoric conditions in the high-temperature orientationally-disordered phase I for samples of different densities. Our isochoric data show a gradual increase of <$ELAMBDA sub V> with temperature whereas isobaric thermal conductivity goes down in this temperature range. The above effect is most clearly expressed in furan, where the atoms in the ring plane are not equivalent, as compared with earlier studied C6H6 and C6H12. The increase of <$ELAMBDA sub V> with temperature can be attributed to weakening of the translation-alorientational interaction which, in turn, leads to a decrease of phonon scattering on rotational excitations. The experimental data are described in terms of a modified Debye model of thermal conductivity with allowance for heat transfer by both low-frequency phonons and "diffuse" modes.