A novel approach for chlorine (Cl) determination in acidic medium using total reflection x-ray fluorescence (TXRF) is reported. It is based on the addition of a known excess amount of AgNO₃ solution to the sample containing Cl for precipitating silver chloride (AgCl). This is followed by TXRF determination of Ag in supernatant after filtering, employing Cd as an internal standard. Tungsten (W) continuum excitation at 50 kV and 38mA was used for TXRFmeasurements. Ag Kα line of the analyte, Ag and Cd Kα line of the internal standard, Cd were used for such determinations of Ag. Six samples of NaCl were prepared in HNO₃ medium of different molarities to obtain the Cl concentrations ranging from 1 to 60 μg/ml. The precision of such TXRF determinations of Cl in nitric acid medium samples was found to be better than 10% (1σ) and the results deviated from the
expected Cl concentrations by less than 15%. An overall laboratory and reagents blank of 1.5±0.5 μg/ml was obtained limiting the applicability of this approach to Cl levels of about 5 μg/ml. This can be improved by using ultra clean laboratory and high purity reagents.