Abstract: Apparatus for the continuous hot tinning of printed circuit boards includes conveying rollers for passing the circuit boards through the apparatus, and a trough for accommodating the molten tin, together with nozzles for applying tin from the trough to appropriate locations on the circuit boards. A hollow column is disposed at at least one side and preferably at both sides of the path of conveying movement of the circuit boards through the apparatus, with the open lower end of the or each column dipping into the trough so as to be below the level of the molten tin therein. Tin is pumped from the trough through the columns by pumps at the lower ends thereof, and then to the nozzles arranged above and below the path of conveying movement and directed so as to spray molten tin on to the printed circuit boards. In a process using the apparatus for soldering the connecting pins of components to a circuit board, molten tin from a trough is sprayed against the underside of the board at the appropriate locations.