We have investigated the Hall electron mobility of GaAsN and the InGaAsN as a function of temperature. The temperature dependence of the electron mobility for the GaAsN system cannot be explained by the alloy and the ionized impurity scattering mechanisms, and the experimental data indicate that unknown scattering mechanisms may be induced by the N incorporation. On the other hand, the temperature dependence for the InGaAsN system shows that the electron mobility improves in the low temperature range in contrast to the case of the GaAsN system. Moreover, the degradation of the mobility induced by the N incorporation is suppressed by the In incorporation, and the alloy scattering becomes dominant as the scattering mechanism in the InGaAsN system. The results strongly suggest that the scattering origin induced by the N incorporation for the GaAsN system may be related with the inhomogeneous N distribution and that the inhomogeneity may be suppressed by the In incorporation. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.