Electron mobility is a term used in solid-state physics to describe how quickly an electron can move through a metal or semiconductor when pulled by an electric field. It is a special case of electrical mobility of charged particles in a fluid under an applied electric field. The drift velocity of an electron for a unit electric field is known as the mobility of the electron. The electron mobility is defined as the ratio of the electron drift velocity to the applied electric field. The SI unit of electron mobility is m²s⁻¹V⁻¹.

The electron mobility is defined by the equation:

μe = vd / E

where E is the magnitude of the electric field applied to a material, vd is the magnitude of the electron drift velocity (in other words, the electron drift speed) caused by the electric field, and μe is the electron mobility. The hole mobility is defined by a similar equation.

Usually, the electron drift velocity in a material is directly proportional to the electric field, which means that the electron mobility is a constant (independent of the electric field) . However, in very large electric fields, mobility depends on the electric field.

Electron mobility may be determined from non-contact laser photo-reflectance technique measurements. In semiconductors, mobility can also apply to holes as well as electrons.