Bi₁₂SiO₂₀ is a technologically important material reported to be extremely stable under high pressure. Here, we report the results of Raman spectroscopic investigations on Bi₁₂SiO₂₀ in the temperature range 300-770 K. The compound remains in the ambient cubic phase in the entire temperature range. Using pressure- and temperature dependence of Raman modes, intrinsic an harmonicity of each of the Raman modes has been calculated.