Many ruthenium-based complexes exhibit unusually high redox activity when promoted to an electronically excited state. The absorption of light by a ruthenium species (ie., tris(2,2'-bipyridine)ruthenium(II) and tris(1,10-phenanthroline)ruthenium(II)) to produce an excited state and subsequent fluorescence/phosphorescence has been known for many years. Information about the nature of this process can be obtained from studies on quenching of the excited state. One of the major quenchers of this system is oxygen, which accepts energy from the triplet state of the excited ruthenium complex. This project sought to determine the quenching abilities of other gas-saturated solutions, and of iodine in solution. Nitrogen, compressed air, oxygen, and carbon dioxide were investigated to determine their effectiveness as quenchers. Of the gases, only oxygen containing solutions showed significant quenching with an averaged rate approximately a factor of two lower than previous studies. Iodine was shown to have a higher quenching rate than oxygen, giving a k_q=8.5 x 10⁹ M^-1s^-1, compared to an average of 1.7 x 10⁹ M^-1s^-1 for oxygen. The iodine quenching rate is compared to a diffusion-limited rate, k_d, calculated via a modified Debye-Smoluchowski equation.