The response in gas exchange and photosystem II (PSII) functions to a flooding condition was characterized with kenaf (Hibiscus cannabinus) by comparing it with napiergrass (Pennisetum purpureum, C₄-plant), corn (Zea mays, C₄-plant) and mungbean (Vigna radiata, C₃-plant). Pot-grown plants were subjected to a 1-week flooding and a 1-week recovery treatment. The flooding treatment had serious effects on the gas exchange of mungbean and corn, while the damages were lenient in kenaf and napiergrass. Kenaf and napiergrass were characterized by keeping a higher stomatal conductance (G_s) and mesophyll conductance (G_m), which resulted in sustaining the CO₂ assimilation under the flooding stress condition. As compared between these two high-yielding species, kenaf was superior in photosynthetic sustainment than napiergrass under the flooding and recovery treatments. The superiority in kenaf is attributable to the fact that this species keeps higher G_s under the flooding, by which photosynthesis was able to continue, and the photosynthetic apparatus prevents the excessive energy accumulation in the leaf. Also, kenaf showed the increase photorespiration and non-photochemical quenching (NPQ) during the treatments.