Single CdTe/CdMgTe quantum well (QW) structures are investigated by stationary and time‐resolved photoluminescence in the presence of an applied magnetic field. We study the dependence of the electron and the holegfactors on the well width by combining Zeeman measurements and the recently developed spin quantum beats technique. The experimental results show that both the electron and the holegfactors have the same sign in wide QWs and increase with decreasing well width. The electron spin phase relaxation time is about 250 ps in our QW structures. ©1996 American Institute of Physics.