The infrared absorption spectrum of the nu(3) (B-Br stretching) mode of HBBr+ has been observed using a tunable diode laser and velocity modulation spectroscopy. The ion was formed in an ac glow discharge through a flowing mixture of H-2 and BBr3. Thirty-three transitions of (HBBr+)-B-11-Br-79 and the same number of lines of the (HBBr+)-B-11-Br-81 isotopomer have been assigned. The band origins and rotational constants are (HBBr+)-B-11-Br-79: nu(0)=937.5696(13) cm(-1), B-0=0.461 822(42) cm(-1), and B-1=0.459 254(41) cm(-1). (HBBr+)-B-11-Br-81: nu(0)=936.0554(11) cm(-1), B-0=0.460 330(45) cm(-1), and B-1=0.457 778(43) cm(-1). Ab initio calculations of the band origins and the internuclear distances have been performed using the GAUSSIAN 94 package. The calculated values are in highly satisfactory agreement with the experimental results.