Speeds of sound in liquid tetrachloromethane and benzene were measured at temperatures from 283.15 K to 333.15 K and pressures up to about 30 MPa. The method used was a sing-around technique employing a fixed path acoustic interferometer operated at a frequency of 2 MHz. The probable uncertainty of the present results is less than +/-0.2 percent taking into account the errors of +/-20 mK for the temperature, and +/-(3 to 5) kPa for the pressure measurements. Measured values are fitted to a polynomial equation as functions of temperature and pressure, and the reliability of the present results is discussed in the light of a comparison with reference data reported in the literature. (C) 2004 Elsevier Ltd. All rights reserved.