The Hall electron mobility in GaAs grown by vapor phase epitaxy (VPE), liquid phase epitaxy (LPE), molecular beam epitaxy (MBE), and metalorganic chemical vapor deposition (MOCVD) has been studied both as a function of temperature (77<T
<300 K) and hydrostatic pressure (0–8 kbar). The analysis of the data shows that in LPE and VPE crystals, the mobilities are lowered due to space‐charge scattering (μSC
) while in MOCVD and MBE samples, a space‐charge‐like limited mobility (μUN
) must be included. The value of the exponent n
has been found to be 1 for MBE and 2 for MOCVD grown samples. It has been concluded that increasing impurity gradation in these layers is responsible for higher values of n
. The pressure coefficient of electron mass in GaAs is determined to be 5.2×10m−4 m@B|
/kbar . The model of central cell scattering due to carbon acceptors fails to account for the experimental data reported in this paper.