1-Methoxy-2-propanol (PGMME) is widely used as an oxygenated additive for diesel fuel. Experimental speed of sound data for PGMME are very scarce. Therefore, the speed of sound in PGMME was measured by the Brillouin light scattering (BLS) method in the temperature range from (306.81 to 648.29) K and pressures up to 10 MPa, including saturated liquid/vapor, liquid, and near-critical and supercritical fluid states. The relative expanded uncertainty (k = 2) of our BLS experimental system is estimated to be less than 1.4%. The variation of the speed of sound with the temperature and pressure is illustrated. Moreover, correlations for experimental speeds of sound in the saturated liquid/vapor and liquid are presented. The correlations represent the experimental data with average absolute deviations of 0.24% for the saturated liquid, 0.19% for the saturated vapor, and 0.36% for the liquid region.