Ab initio configuration interaction calculations are carried out for eight low-lying (1,3)Pi(u), and four (1) Delta(u) states of the O-2 molecule. Three different types of couplings an considered : nonadiabatic, spinorbit, and rotational, and the complex scaling method has been employed to determine rovibrational energies and wave functions. The calculations correctly predict a large number of trends in the measured level locations, predissociation linewidths, rotational constants, and line intensities for the (4p sigma) (1,3)Pi(u) states. It is found that the upsilon = 1 level has the lowest frequency and strongest absorption intensity among the four observed vibrational levels of the (4p sigma) (3) Pi(u) state, while the upsilon = 2 has the broadest predissociation linewidth and upsilon = 0, the smallest rotational constant, all in agreement with experimental findings. The linewidth of the upsilon = 0 level of the (1) Pi(u) state is computed to be 0.01 cm(-1), consistent with the measured value of less than 0.1 cm(-1). The calculations indicate that the upsilon=0 level of the (4p sigma) (1) Pi(u) state borrows intensity from the allowed (4p sigma) (3) Pi(u)-X-3 Sigma(g)(-) through spin-orbit interaction and that the upsilon = 4 level of the (4p sigma) (3) Pi(1u) component, which has not yet been identified experimentally, is strongly perturbed by the upsilon = 3 level of the (4p sigma) (1) Pi(u) state. The L-uncoupling-type interaction between (1) Pi(u) and (1) Delta(u) states is also studied, and the explanation for the missing lines of the upsilon = 0, J greater than or equal to 2 rovibrational levels of the (4p sigma) (1) Pi(u) states is sought based on the calculated results.