The temperature (T) dependence of the absorption coefficient &bgr; at 10.6 &mgr;m of Czochralski‐grown high‐resistivity GaAs and chemical vapor deposited (CVD) ZnSe is measured by laser calorimetry. Experimental data are compared with theoretical curves for intrinsic multiphonon absorption. The temperature dependence of &bgr; for GaAs is found to possibly exhibit multiphononlike behavior below ∼450°K, but deviates rapidly from theoretical predictions above ∼500°K. The latter effect may be attributed to an increase in free‐carrier density via thermal ionization from a level near 0.37 eV. The absorption coefficient of CVD ZnSe is found to be independent ofTover the temperature range investigated, and therefore this material appears to be impurity or surface loss dominated.