Synthesis and upconversion luminescence properties of the new BaGd2(MoO4)(4):Yb3+,Er3+ phosphor were reported in this paper. The phosphor powder was obtained by the traditional high temperature solid-state method, and its phase structure was characterized by the XRD pattern. Based on the upconversion luminescence properties studies, it is found that, under 980 nm semiconductor laser excitation, BaGd2(MoO4)(4):Yb3+,Er3+ phosphor exhibits intense green upconversion luminescence. which is ascribed to H-2(11/2) --> I-4(15/2) and S-4(3/2) --> I-4(15/2) transition of Er3+. While the observed much weaker red emission is due to the non-radiative relaxation process of S-4(3/2) --> F-4(9/2) and F-4(9/2) --> I-4(15/2) transition originating from the same Er3+. The concentration quenching effects for both Yb3+ and Er3+ were found, and the optimum doping concentrations of 0.5 mol% Yb3+ and 0.08 mol% Er3+ in the new BaGd2(MoO4)(4) Gd3+ host were established. (C) 2009 Elsevier Ltd. All rights reserved.