Compressional wave attenuation, Qp-1 , and velocity, Vp , for an alkalic olivine basalt have been measured from 1250¿ to 1450 ¿C and from 5 to 10 MHz by an ultrasonic interferometric technique. Vp shows no significant frequency or temperature dependence, and Qp-1 increases with increasing frequency and decreasing temperature. For the conditions of this study, the melt can be modeled as a viscoelastic material with a single thermally activated structural relaxation mechanism having an activation energy of 2.2 eV and a relaxation time on the order of 1 ns. The data presented here fall in the region of the relaxation spectrum where the frequency, f, is much smaller than the relaxation frequency, and the absorption coefficient is proportional to f 2. Analysis of the data suggests that (1) compressional wave losses will be negligible in a basalt melt at seismic frequencies, and (2) the volume viscosity of basalt melt is comparable in magnitude to shear viscosity.