AbstractDehydrogenative coupling reactions of naphthols and phenols were achieved with a heterogeneous catalyst, alumina‐supported ruthenium hydroxide (Ru(OH)x/Al2O3), using continuous‐flow conditions and aerobic oxygen as the sole oxidant. The reactions were operated continuously for more than 16 h with good reactivity and selectivity. The Ru catalyst could be recycled at least three times by a simple online washing/activation procedure without depackaging the catalyst cartridge. The reaction provided binaphthols and biphenols as valuable products for synthetic purpose and functional materials, while an over‐oxidized quinone was obtained with 2,6‐Di‐tert‐butylphenol; combining this reaction with catalytic hydrogenation under continuous‐flow conditions enabled smooth conversion of quinone to the 4,4′‐biphenol derivative, which is a member of an important class of compounds for liquid crystals, engineering plastics, and other functional materials.