The thermal The thermal conductivity of some selected cabal (CaO.B2O3.Al2O3) glasses was measured by the steady state method. Experimental results reveal variation of the thermal conductivity with the change in glass composition by the progressive replacement of CaO by any of the monovalent oxides Li O, Na O or K O. The results are discussed in terms of the J 2 2 2 possible change in the compactness or rigidity of the glass structure with the change in chemical composition, which may virtually affect the phonon mean-free path responsible for thermal conduction.