The relationships of cathode reactions in trivalent chromium electrodeposition process were analyzed.A mathematics model was established to testify the relationships between Cr3+ ions concentration

diffusion intensity

temperature and the deposition rate of Cr3+ by mathematic methods.The results show that the limited current density of the reaction Cr3++e → Cr2+ is controlled by diffusion step.Intensifying the diffusion condition leads to more Cr2+ produced

which results in the accumulation of Cr2+ in the electrolytes bulk.The reaction of Cr2++2e → Cr0 is the rate control step of the whole trivalent chromium electrodeposition

and the limited current density is independent of the diffusion condition.The key of intensifying the trivalent chromium deposition is to accelerate the charge transfer in the Cr2+ reduction step by the addition of organic bridged ligands into the electrolyte.