Using deep-level transient spectroscopy (DLTS) and admittance spectroscopy we investigated nitrogen doped ZnSe and ZnSSe layers grown onp-type GaAs substrates by molecular beam epitaxy. Three major hole traps denotedT1,T2,andT3were observed with energy levels at 0.11, 0.46, and 0.56 eV from the valence band, respectively. Similar energy levels were observed in nitrogen doped ZnSSe except thatT1was at 0.12 eV from the valence band. A crude estimation of the 0.11 eV trap concentration obtained from DLTS data shows correlation with the free carrier concentration due to nitrogen. We attributeT1to a nitrogen acceptor which controls thep-type conduction in the materials. No other direct observations of this important acceptor level have been reported in the literature so far. The two remaining levels may originate from the nitrogen doping process. We also point out the effect of the series resistance observed in this kind of material. ©1998 American Institute of Physics.