In this study, the effects of microwave (MW) processing of Brussels sprouts on various bioactive compounds, moisture content, and antioxidant capacity were studied. Brussels sprouts was processed at three different MW output powers (460, 600, and 700W), and then kinetic study for the degradation of the total chlorophyll, vitamin C, total polyphenols, total flavonoids, antioxidant capacity, and two phenolic acids (sinapic and ferulic acid) was conducted. According to the results, MW processing caused significant reductions in analyzed bioactive compounds, moisture content, and antioxidant capacity. It was found that HPLC analysis results confirmed the result of the spectroscopic analysis. Zero-order and first-order kinetic models were fitted to experimental data. The first-order kinetic model was selected as the best according to R-2, RMSE, and (2). The degradation rate constant (k) for all analyzed properties increased as the MW output power increased from 460 to 700W, and it could be concluded that the MW output power in which bioactive compounds, moisture content, and antioxidant capacity of Brussels sprouts were best preserved was 460W.