Hydrogen gas (H₂) functions as an important signaling molecule in diverse plant developmental processes. H₂ is thought to delay postharvest ripening and senescence in fruit. However, little is known about the influence of H₂ on flower senescence. This study was conducted to determine whether H₂ treatment could improve vase life and quality in cut lily (Lilium spp.) and rose (Rosa hybrid L.) flowers. Treatment with 0.5% and 1% hydrogen-rich water (HRW) increased vase life and maximum flower diameter in lily. In addition, 50% HRW treatment significantly increased vase life and maximum flower diameter in cut rose flowers. The fresh weight and leaf relative water content in cut lilies and roses were enhanced by proper doses of HRW. Compared with the control, HRW treatment decreased leaf stomata size in cut lily and rose flowers. HRW treatment significantly reduced leaf malondialdehyde contents and electrolyte leakage in cut lilies. Antioxidant enzyme activities were also improved by HRW treatment in cut lily and rose flowers. These results suggest that exogenously applied H₂ might improve vase life and postharvest quality in cut flowers by maintaining proper water balance and membrane stability and by reducing stomata size and oxidative damage.