We report speeds of sound in n-pentane measured using two similar apparatuses, located at Ruhr University Bochum (RUB) and Imperial College London (ICL), covering different ranges of temperature and pressure. At RUB, measurements were conducted at temperatures from (233.50 to 353.20) K with pressures up to 20 MPa, while temperatures from (263.15 to 473.15) K with pressures up to 390 MPa were covered at ICL. Accounting for the uncertainties in temperature, pressure, path-length calibration, and pulse timing, the relative expanded combined uncertainty (k = 2) in the speed of sound varied from 0.015% to 0.18% over the whole region investigated.Nevertheless, small differences averaging at 0.13% are found between the two data sets in the region of overlap. The experimental data reported in this work have been partly used in the development of a new fundamental equation of state for n-pentane.