The (A) over tilde (2)Pi(u)-(X) over tilde (2)Pi(g) electronic band system of jet-cooled boron disulfide (BS2) has been recorded in the 760-530 nm region by laser-induced fluorescence (LIF) and wavelength resolved emission techniques. The free radical was produced in a pulsed electric discharge jet using a precursor mixture of BCl3 and CS2 in argon. The LIF spectrum consists of a long progression of strong bands involving the nu(1)(') (B-S stretching) mode and combinations involving 2nu(2)(') and 2nu(3)('), as well as many hot bands built on the 2(1)(1) band. Detailed analysis of the spectrum shows that the ground state exhibits a substantial Renner-Teller effect with epsilon=-0.2012 and a spin-orbit coupling constant of A=-413.80 cm(-1). Angular momentum coupling is negligible in the excited state, which has a much smaller spin-orbit coupling constant of A=-259.15 cm(-1). The vibrational frequencies of (BS2)-B-11 are omega(1)(')=542.8, omega(2)(')=285.0, omega(3)(')=1010.5, omega(1)(')=514.1, omega(2)(')=309.7, and omega(3)(')=1543.6 cm(-1). Rotational analysis of the 0(0)(0) band allowed a determination of the effective molecular structures as r(0)(')(BS)=1.6648(4) Angstrom and r(0)(')(BS)=1.7127(5) Angstrom. Ab initio methods have been used to predict the BS2 spectroscopic parameters and good agreement with experiment was found. Our present understanding of the LIF spectrum is in accord with the pioneering analysis of the absorption spectrum of matrix isolated BS2 published by Brom and Weltner [J. Mol. Spectrosc. 45, 82 (1973)] three decades ago. (C) 2003 American Institute of Physics.