Terbium activated gadolinium oxysulphide phosphor (Gd2O2S: Tb) shows bright green luminescence and high efficiency under X-ray excitation. Phosphor utilisation depends on powder characteristics and luminescence properties that are regulated during the synthesis stage. The paper presents some of our new results referring to the synthesis of Gd2O2S: Tb phosphor by solid state reaction route from oxide precursors. Efficient luminescent powders utilisable