Rapid and accurate determinations of limestone in lime products would be useful for process control applications in the lime industry. The loss-on-ignition method commonly used for determining residual limestone is very time consuming and prone to error. In this study, the feasibility of using photoacoustic spectroscopy (PAS) as a process control tool in the lime industry was investigated. Results from preliminary PAS measurements on samples prepared in the laboratory indicated that a low-cost dedicated analyzer employing PAS has excellent potential.