Time-domain coherent Raman techniques have been utilized to selectively measure ultrafast decay rates of optical phonons in cubic BaSnO3 perovskite. Measurements were made within a 350–1300 cm−1 frequency range with time and equivalent spectral resolution of ∼120 fs and less than 0.1 cm−1, respectively. The phonon mode damping rates are found to be within 1.27–1.59 ps−1 at room temperature, indicating that the homogeneously broadened Raman linewidths are within 6.7–8.4 cm−1. Phonon decay mechanisms are being discussed within the framework of parametric phonon interactions due to lattice anharmonicity. Characteristics of the Raman active modes are essential in understanding the limiting factors for achieving high carrier mobility in device applications of the material.