The detection of C60 and C70 fullerenes in young planetary nebulae (Cami et al. 2010; Garcia-Hernandez et al. 2010) and in reflection nebulae (Sellgren et al. 2010) suggest that these molecules are more common in certain astrophysical environments than thought before. The dependence on temperature of the positions and widths of the infrared bands of the C60 and C70 fullerenes is needed for a firm qualitative detection of these molecules in space. Furthermore, the integrated molar absorptivity Ψ (in Km/mol) of each infrared absorption band is required for a quantitative determination of the abundance of C60 and C70 in space. The present work reports on the temperature dependence of the wavelength shift and integrated molar absorptivity of the infrared bands of C60 and C70 fullerenes. The measurements were made in a KBr matrix in a wide range of temperatures comprised between -180°C and +250°C. The experimental data were extrapolated to absolute zero for both the infrared band shift and the integrated molar absorptivity of C60 and C70 fullerenes.