The Hall mobility of GaAsN layers grown by liquid phase epitaxy (LPE) is studied as a function of the nitrogen content in the material. It is observed that the parameter decreases with increasing nitrogen in the layer, in agreement with earlier theoretical predictions assuming scattering of electrons in nitrogen-related defects. It is also found that the decrease in mobility is accompanied by a corresponding increase in the density of electron traps, believed to originate from different configurations of nitrogen defect centers. The observation clearly suggests that nitrogen-related defects are responsible for lowering the mobility in LPE-grown GaAsN. © 2008 IOP Publishing Ltd.