The high-resolution infrared emission spectrum of boron monofluoride was recorded with a Fourier transform spectrometer. There are 359 transitions of 11BF with ν = 1 → 0 to ν = 5 → 4, and 94 transitions of 10BF with ν = 1 → 0 to ν = 3 → 2 assigned. Improved Dunham Y ij coefficients for the ground X1Σ + electronic state were determined from the infrared data combined with existing microwave data. The mass-reduced Dunham U ij coefficients were also obtained along with Born-Oppenheimer breakdown constants. An effective Born-Oppenheimer potential was determined by fitting the available data to the eigenvalues of the radial Schrödinger equation containing a parameterized potential function. Finally, the relative transition dipole moments of the major isotopomer 11BF were also measured. For AlF, our previous measurements were extended to higher ν and J, in order to obtain improved Dunham coefficients and an improved internuclear potential.