Methane tri-reforming is considered as a highly efficient process for syngas production. In this paper, a fluidized-bed tri-reformer reactor (TR), which is a suitable alternative for conventional steam reformer (CSR) and auto thermal reformer (CAR), is optimized. A mathematical heterogeneous model is applied to simulate the reactor and the model is validated using the plant data. After determining the optimal operating conditions through differential evolution (DE) method, the performance of the proposed reactor is assessed through evaluating the methane conversion, hydrogen production and desired H-2/CO ratio. Methane conversion, hydrogen yield and H-2/CO ratio are 99.4%, 2.1 and 1.84, respectively. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.