Promoter modified porous iron-based microspheres were prepared through one pot solvothermal method, and employed as catalysts during Fischer-Tropsch (FT) synthesis. Specially, a microsphere was consist of nanoparticles and pores. The effect of promoter and pore on CO conversion and on lower olefins selectivity was investigated. Fe/K and Fe/Zn displayed a high selectivity to CH4 (>0 wt%), which was not desirable for their application in the FT process. Na doped Fe/Na catalyst displayed optimum catalytic performance. In particular, it showed an excellent selectivity toward C5+ (59.0 wt%) while yielding a CH4 product fraction lower than 11.3 wt%. Fe/Mn catalyst showed a C2-4 olefins selectivity approximately 34.1 wt%, but only achieved a CO conversion of 37.4%. Furthermore, the results showed that pore size of catalysts played a key role on morphology of catalysts and on catalytic performance with time on stream. (C) 2015 Elsevier B.V. All rights reserved.