Triplet states of the CO molecule in the region between 86 000 and 94 000 cm(-1) have been investigated in a 1+1 double-resonance experiment using a detection scheme based on laser-reduced fluorescence (LRF). The strongly predissociated (3 rho sigma) j (3) Sigma(+) Rydberg state at 90 833 cm(-1) with an average lifetime of 4.6 ps has been observed spectroscopically at high resolution for the first time, providing a clear identification of this state. Both the accidental predissociation of the J(f)=6 level of CO (E (1) Pi, upsilon = 0) and the value of the lambda-doubling constant q of the c (3) Pi state can be attributed to j (3) Sigma(+). In addition, a valence state around 91 960 cm(-1) has been identified as (3) Pi. Accurate molecular constants have been determined for both states.