[en] We present photoluminescence (PL) studies of Cl-doped Zn_1-xBe_xSe (x=0-0.029) alloys performed in wide ranges of temperature (10-296 K) and of excitation intensities. We show that the high-temperature PL is characterized by a free-to-acceptor-type transition, involving shallow state of the localized holes. We shall show that similar transitions are also present in comparable undoped samples, but the PL intensity is substantially lower. Finally, we show that the ionization energy of the relevant acceptor-like species increases with Be concentration, suggesting an effective mass type defect