The effects of carbon black dispersion on particle size and catalytic activity of silver catalyst was investigated. Sodium dodecylbenzenesulfonate was added in AgNO₃ and NaBH₄ solution, and obtained colloidal solution was mixed with dispersed carbon black for impregnation. Dispersity of carbon black were investigated by poresize distribution and reagglomeration was appeared after homogenizing 30 seconds. The catalytic activity were measured by chemisorption and electrochemical method. The aggromeration of silver particle was influenced with surfactant amount, stirring time and heat treatment.