Photocatalytic hydrogen generation is a viable option among strategies to mitigate the energy crisis. This study investigates visible-light-driven H2 generation using Ag-doped twin crystal CdxZn1-xS photocatalysts synthesized through a solvothermal process. Ag nanoparticles induce Surface Plasmon Resonance (SPR), enhancing photo-response. Twin crystal 1 wt% Ag-doped Cd0.5Zn0.5S photocatalyst exhibits significant H2 evolution at 2458 μmol/gcat.h under visible light. Enhanced performance is attributed to dual-function Ag nanoparticles: SPR-enhanced light absorption, efficient electron transfer to the Cd0.5Zn0.5S conduction band, and the twin crystal structure facilitating electron-hole pair separation. Emphasis on optimal Ag loading and the crucial role of SPR in elevating photocatalyst efficiency.