In this study, the synthesis parameters of magnesium fluoroborate, one of the special boron compounds, were determined and its flame retardant property in cotton fabric was investigated. In addition, kinetic studies were carried out to calculate the reaction order and activation energy. Magnesium fluoroborate was synthesized by wet method using magnesium carbonate and fluoroboric acid as reactants. The effects of reactant mole ratios (nMgCO(3)/nHBF(4)), temperature and reaction time on the reaction yield were investigated. FT-IR, XRD, TGA and BF4- ion selective electrode were used for characterization studies. Magnesium fluoroborate was synthesized with 98% yield when the mole ratio, temperature and reaction time are set as 1:3, 50 degrees C and 90 min, respectively. In addition, kinetic experiments reveal that the reaction obeys to first order kinetics and the activation energy was found as 6.75 kJ/mol. LOI test was used to determine the flame retardant property of synthesized magnesium fluoroborate. LOI test results proved that the magnesium fluoroborate has noteworthy flame-retardant property.