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Steel slag, a waste from steelmaking plant, has been proven to be good candidate resources for low-cost calcium-based CO 2 sorbent derivation. In this work, a cheap and sintering-resistance CaO-based sorbent (CaO (SS)) was prepared from low cost waste steel slag and was applied to enhance catalytic steam reforming of coke oven gas for production of high-purity hydrogen. This steel slag-derived CaO possessed a high and stable CO 2 capture capacity of about 0.48 g CO 2 /g sorbent after 35 adsorption/desorption cycles, which was mainly ascribed to the mesoporous structure and the presence of MgO and Fe 2 O 3. Product gas containing 95.8 vol% H 2 and 1.4 vol% CO, with a CH 4 conversion of 91.3% was achieved at 600 °C by steam reforming of COG enhanced by CaO (SS). Although high temperature was beneficial for methane conversion, CH 4 conversion was remarkably increased at lower operation temperatures with the promotion effects from CaO (SS), and CO selectivity has been also greatly decreased. Reducing WHSV could increase methane conversion and reduce CO selectivity due to longer reactants residence time. Reducing C/A could increase methane conversion and hydrogen recovery factor, and also decrease CO selectivity. When being mixed with catalyst during SE-SRCOG, CaO (SS) with a uniform size distribution favored methane conversion due to the high utilization efficiency of catalyst. Promising stability of CaO (SS) in cyclic reforming/calcination tests was evidenced with a hydrogen recovery factor >2.1 and CH 4 conversion of 82.5% at 600 °C after 10 cycles using CaO (SS) as sorbent. • Synergistic resource utilization of coke oven gas and steel slag. • Sintering-resistance CaO-based sorbent was derived from waste steel slag. • H 2 recovery factor >2.7 was achieved at 600 °C by SE-SRCOG. • Product gas containing 82 vol% H 2 was still obtained after 10 cycling tests. [ABSTRACT FROM AUTHOR]