Resistance welding is used extensively in manufacturing industries, the most popular being spot welding in the automotive industry. Despite spot welding being in use for over a century, there has been relatively little development of sensors for monitoring the process in real-time. Most existing systems use current, voltage and electrode force to give an indication of welding quality, however these systems do not provide warning of changes in the welding environment. These changes could include material variability or electrode condition, which could result in weak weld nuggets. Presented in this paper is an investigation of a system that utilises an array of sensors, including current, voltage, infrared and ultrasonic that is capable of monitoring the spot welding process as it is performed. This system utilises wireless sensor technology to transmit data from the welding arms to a sensor connected to a base computer where the data can be analysed. The wireless link is particularly useful when retrofitting the sensor cluster to existing installations.