Reactive distillation/absorption is among multifunctional reactors for process intensification. Conventionally, reactive distillation/absorption is suitable for liquid-phase catalytic reaction, with rare reports for gas-phase catalytic reaction. By reviewing the conventional reactive distillation/absorption concepts, we re-classify RD/A based on the criterion of phase state; and by analyzing the recent advances of column trays and catalyst development etc., we put forward novel conceptual design to conveniently achieve gas-phase catalytic reaction in reactive distillation/absorption process, which is termed as Gas-phase Catalytic Reactive Distillation/Absorption (GC-RD/A). The feasibility of this concept in theory and practice are analyzed from the perspective of catalyst, reactive internals and phase states. Practical challenges are presented comprehensively including equipment design, flow patterns, transport phenomena, reaction selection and operation window, and catalyst design, from fundamentals to industrial implementation.