Acoustic absorption in p-dichlorbenzene and naphthalene single crystals was measured from room temperature to −70°C in the frequency range 5–95 MHz. A frequency-squared dependence of the absorption values was observed in both crystals, and comparisons are given with the values calculated by the resonance absorption theory suggested by Liebermann [Phys. Rev. 113, 1052 (1959)] for a benzene single crystal. The temperature dependence of the absorption coefficient α is similar in the two crystals, with α decreasing slightly as the temperature increases above −40°. This dependence is similar to that observed by Rasmussen for a cyclohexane single crystal [SIO Ref. 61-1, Scripps Inst. Oceanog. Marine Physical Lab. (April 1961)]. The value of α measured in the two cases was about two orders of magnitude smaller than those obtained by Liebermann and Rasmussen, and was approximately the same size as those observed for some metal single crystals at room temperature. However, other absorption processes, such as thermal conduction and dislocation damping, were ruled out as possible sources of the attenuation by experimental tests. [Supported by U. S. Office of Naval Research.]