A concentrate of a palladium-tin colloidal catalyst is obtained by dissolving stannous chloride in HCI, diluting the solution with HCI and then further diluting the solution with deionized water to thereby obtain a diluted stannous chloride solution. This solution is cooled to room temperature or below. A palladium chloride solution is obtained by dissolving palladium chloride in HCI which in tum is also cooled to room temperature or below. The palladium chloride solution is gradually added to the stannous chloride solution and mixed at about room temperature in order to obtain a homogeneous solution. The temperature of the solution is then gradually increased to about 105°C to about 110°C and maintained at that temperature for sufficient time to obtain a homogeneous solution of substantially uniform colloidal particles. The solution of colloidal particles is slowly cooled to about room temperature. The palladium-tin colloidal system is produced reproducibly and is applicable in the manufacturing of highly complex circuitry.