This paper presents a comprehensive collision-induced dissociation and ab initio study of small boron oxide cations, BnOm+, motivated by a need for more accurate and reliable structural and thermodynamic information on both neutral and ionic boron oxides. Absolute fragmentation cross sections were measured for all observable BnOm+ (n < 4, m < 5) parent ions at center-of-mass collision energies ranging from 0.08 to 10 eV. Quantitative dissociation thresholds, generated from the experimental data by correcting for the collision energy spread resulting from the beam energy distribution and the thermal motion of the target gas, are compared to ab initio dissociation energies determined from Gaussian-2 calculations.