Ce-doped YAG (Y3-xAl5O12:xCe, YAG:Ce) phosphor were prepared by co-precipitation method using ammonium hydrogen carbonate as a precipitant. The influence of precipitation condition such as pH on the powder properties and the optimum Ce content in YAG:Ce were investigated. Throughout the experiment, phase pure YAG:Ce powders with 5070nm particle sizes were obtained. The luminescence intensity and particle size increased as calcination temperature increased in the range of 9001300C. The maximum luminescent intensity was observed at 2mol % of Ce concentration in the YAG:Ce phosphor. The luminescent intensity the YAG:Ce particles was significantly affected by the pH of the precipitation condition. Within the scope of this study (pH 5-8), the lower pH was favored for the higher emission intensity. The phosphors prepared had maximum excitation band at 467nm and a maximum emission band at 525530nm.