In this work we report a systematic study of the electron and hole mobilities of GaNxAs1-x alloys with different dopants (Zn, Te) and carrier concentrations (1017-1019 cm-3). We found a very slight reduction of the hole mobility in p-GaNxAs1-x compared to p-GaAs, indicating that for small N contents (∼1.6%) the valence band is not affected by the N incorporation. In a striking contrast, incorporation of even small amounts of N leads to an abrupt reduction of the electron mobility in n-GaNxAs1-x. We further show that the processes that limit the mobility in GaNxAs1-x can be explained by the band broadening and the random field scatterings. Considering these two scattering mechanisms we calculated the dependence of electron mobilities on electron concentration as well as on N composition in GaNxAs1-x. The calculations agree reasonably well with experiment data of maximum electron mobilities with alloy composition. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)