Thomas played 39 minutes and hit 8-of-13 field goals, including 4-of-7 from beyond the arc, for the Buckeyes (12-3, 2-1 Big Ten), who bounced back from a weekend loss to Illinois.
Aaron Craft contributed 15 points and Evan Ravenel scored 13 for the Buckeyes, who shot a sizzling 56.4 percent from the field and out-rebounded Purdue (7-8, 1-2) 36-27.
The Boilermakers lost their second consecutive game, shooting 38.8 percent from the field. Terone Johnson led the Purdue offense with 18 points.
Ohio State led 39-29 and kept Purdue at arm's length the rest of the way as both teams scored 35 points in the second half.