A procedure is proposed for the simultaneous FTIR determination of propyphenazone (PFZ) and caffeine (CAF) in pharmaceuticals. The method involves the dissolution of the active principles in CHCl3, followed by filtration of sample solutions to remove the excipients. PFZ is then determined by absorbance measurements at 1595 cm-1, using a baseline established between 2000 and 890 cm-1, and CAF by using the first-derivative values at 1712 cm-1, using solutions of PFZ and CAF for external calibration. The method was applied in both the stopped-flow and flow-injection modes, providing precise and accurate results for the analysis of real samples. The incorporation of a distillation unit for the on-line recycling of the CHCl3 used as carrier and solvent provides an environmentally friendly analytical methodology which makes possible an injection frequency of 120 samples h-1 and reduces the cost and side-effects of the production of laboratory waste.