It is still a great challenge that designing proper codoping concentrations of rare earth ions for achieving intensest expected emission from the studied phosphor. In this work, the quadratic general rotary unitized design (QGRUD) was introduced into the codoping concentration option of NaLa(MoO4)(2): Er3+/Yb3+ phosphor for upconversion (UC) applications, and the optimum doping concentrations of Er3+ and Yb3+ for achieving maximum UC luminescence intensity, which is close to commercial NaYF4:Er3+/Yb3+ phosphor, were obtained. The two-photon process was assigned to the green UC emissions in the optimized NaLa(MoO4)(2): Er3+/Yb3+ phosphor. It was also demonstrated that the optimized phosphor presented more stable upconversion emissions than the commercial NaY4:Er3+/Yb3+ phosphor. (C) 2015 Elsevier Ltd. All rights reserved.