High doping regimes of B implanted Ge have been accurately characterized combining Hall effect technique and nuclear reaction analysis. Preamorphized Ge was implanted with B at 35keV (spanning the 0.25–25×1020B∕cm3 concentration range) and recrystallized by solid phase epitaxy at 360°C. The Hall scattering factor and the maximum concentration of active B resulted rH=1.21 and ∼5.7×1020B∕cm3, respectively. The room-temperature carrier mobility was accurately measured, decreasing from ∼300to50cm2∕Vs in the investigated dopant density, and a fitting empirical law is given. These results allow reliable evaluation for Ge application in future microelectronic devices.