Theoretical and experimental studies of the electron mobility and the free‐carrier absorption ofn‐type InP were carried out in the temperature range 77–300 °K. All major scattering processes and screening effects were taken into consideration. It was found that the experimental dependence of electron mobility and free‐carrier absorption on temperature and/or on carrier concentration can be consistently explained only when the effect of compensation is quantitatively taken into account. Convenient procedures are presented for the determination of the compensation ratio from the values of electron mobility and from the free‐carrier absorption coefficient. The high contribution of optical‐phonon scattering in InP limits the applicability of the free‐carrier absorption approach to electron concentrationn≳1017cm−3. Electron mobility, however, can be reliably employed for the determination of the compensation ratio forn≳1017cm−3at 300 °K andn≳1015cm−3at 77 °K.