Titanium dioxide is well known for its strong photocatalytic property, but mainly works in the UV range. In this study, rutile, the less photocatalytic type among the three different titanium dioxide crystal structures, was suspended in acetonitrile and treated by oxygen and argon plasmas using the novel dense medium plasma technology. During the plasma treatment, rutile particles were doped with trace elements due to the use of electrodes made from different metals. The subsequent photoactivity analyses show that the modified rutile is almost as photocatalytic as anatase, the most photoactive type of titanium dioxide. In addition, the change in color after plasma treatment indicates that the modified rutile absorbs visible lights and may work as photocatalyst in the visible range. Given the fact that rutile is available more readily and cheaper than anatase, these results are very encouraging and open up possibilities in using rutile for photocatalytic applications.