Boron compounds are generally highly volatile, and some of them vaporize in coal combustion and are contained in the flue gas. The partitioning behavior of boron from coal to the flue gas depends on the coal type, and the partitioning mechanisms are complex. In order to elucidate these mechanisms, it is necessary to develop a method to measure gaseous boron in coal combustion flue gas. In this study, we examined the absorption solution and sampling system material for gaseous boron compounds, using a model system of gaseous boron compounds and flue gas from a practical coal combustion facility. As a result, nitric acid with hydrogen peroxide was found to be the optimum solution for absorption. Silica glass or ethylene tetrafluoride resin were suitable materials for the sampling probe and line and the absorption impinger. Additionally, the sampling line must be kept at more than 130 degrees C in order to analyze the gaseous boron concentration accurately.