The viability of employing flow analysis coupled to Fourier transform infrared spectroscopy (FA-FTIR) as a useful tool for quantitative measuring of magnesium sulphate in pharmaceuticals was explored, developed and validated. The method was based on mid-IR transmittance measurements of the peak-area belonging to the sulphate band around 1110 cm–1 and the use of an external calibration curve. Dynamic range was established over a concentration range from 1 to 50 mg.ml–1 , with a limit of detection (3σ) of 0.26 mg.ml–1 The analytical frequency was 12 h–1 with a precision close to the unit (% RSD). The . analytical results obtained in commercial formulations by applying the proposed FA-FTIR method were in strong agreement with labelled values and those obtained by a reference titration method at 95% confidence level. Among various advantages offered by the proposed method over conventional ones, simple strategy and clean analytical chemistry must been highlighted.