AbstractFirst investigations are reported on the temperature dependence of the dc‐conductivity atT= = 0.05 to 300 K on neutron‐transmutation‐doped (NTD) n‐GaAs in the vicinity of the metalinsulator transition (MIT). At a medium compensation ofK= 0.60 to 0.77 the MIT takes place at the critical electron concentration ofnc= 2.3 × 1016cm−3. On the dielectric side of the MIT in the variable‐range hopping regime (VRH) atT≦ 10 K the conductivity obeys the equation σ(T) = σ0exp [— (T1/T)1/2] and not the Mottlaw. The experimental valuesT1are for all samples much smaller thanT1theorfor isolated shallow impurities and scale down according toT1= =T1*(1 ‐n/nc)1.6±0.4withT1* = 5.9 K by approaching the MIT. This behaviour is due to the divergency of the localization radiusaand the static DK ϵ0at the MIT. The obtained linear In σ —T−1/2law over about 2.5 orders of magnitude in temperature variation and more than three orders of magnitude of variation in conductivity is interpreted in the frame of a Coulomb gap with vanishing density of states at the Fermi level, as predicted by Efros and Shklovskii. The pre‐exponential factor ϱ0= σ0−1shows also scaling behaviour according to ϱ0= ϱ0*(1 ‐n/nc)1.2±0.4and a value of ϱ0* = 2.2 Ω cm. Atn→ncσ0= ϱ0−1reaches the value of Mott's minimal metallic conductivit