Density measurements conducted for the binary systems of butan-1-ol (1) + n-octane (2) and butan-1-ol (1) + n-decane (2) at high pressures are presented in this work. These measurements were conducted utilizing an Anton Paar DMA HP densitometer and encompass the entire composition range, with a temperature and pressure range of T = (313.15-353.15 K) and P = (0.1-20 MPa), respectively. The modified Toscani-Szwarc equation of state was employed to successfully correlate the experimental density data. The measured data were observed to comply with general expected trends with regards to the relationship between density, temperature, and pressure. Derived thermodynamic properties, namely, excess molar volumes, thermal expansivity, and isothermal compressibility, are also presented. Deviations from ideality are attributed to differing molecule sizes and shapes as well as intermolecular interactions between components constituting the mixture.