MLB.com first reported earlier this month of the Reds' interest in Sizemore.
"Still working on it," Reds general manager Walt Jocketty said Sunday in a text message.
Sizemore, 31, has not played in the Majors since 2011 and had microfracture surgery performed on both of his knees during his injury-riddled career.
After losing Shin-Soo Choo as a free agent, the Reds are planning to have prospect Billy Hamilton compete to be the everyday center fielder and leadoff man. But the club is also looking to add insurance behind the inexperienced Hamilton.
Sizemore, a three-time All-Star, is a career .269 hitter with 139 home runs, 458 RBIs and a .357 on-base percentage over eight big league seasons in Cleveland. From 2006-08, he batted .279 with a .380 on-base percentage, averaging 28 home runs per season.
Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.