In this paper, the ICP-OES method (induced coupled plasma optical emission spectrometry) was used to determine the content of silicon dioxide in bauxite, as an important impurity that affects the quality and application of bauxite in alumina production by the Bayer process. Twenty bauxite samples from seven different deposits were analysed. The results were compared with the reference spectrophotometric UV-VIS method. For both methods, bauxite samples for analysis were prepared by melting with a mixture of sodium carbonate: sodium tetraborate 3: 1. The molten mass was then dissolved in 1: 3 hydrochloric acid. The calibration curve was prepared from a single element silicon ICP standard solution, concentration 1000 mg dm-3 of Si. The mean relative difference between the silicon dioxide content determined by the ICP-OES method and the reference method is found to be 4.88%. Statistical tests were used to assess the comparability of two methods, followed by a scatter plot, the Bland Altman, Passing-Bablok, and the Mountain plot. Graphical comparisons generally do not show statistically significant differences between methods. The accuracy and precision of the ICP-OES method were verified using the standard reference material SRM NIST 697, Dominican Bauxite. Recovery and repeatability values, expressed as RSD, are within the acceptance criteria. Based on the t-test, there is a statistically significant difference between the mean value of ICP-OES measurements and the certified value of silicon dioxide, which can be attributed to the effect of systematic error of ICP-OES analysis.