The 36-year-old Hernandez signed a two-year, $6.4 million contract before last season. But he hit only .217 with five homers and 28 RBIs in 52 games for the Rockies in 2012.
The Rockies purchased the contract of Yorvit Torrealba on Friday to be their backup catcher. This will be Torrealba's second stint with the Rockies. He was with Colorado from 2006-09. Torrealba hit .227 with three teams in 64 games last year.
Colorado also purchased the contract of right-hander Chris Volstad and designated righty Will Harris for assignment.
The Rockies have additionally optioned outfielder Tyler Colvin to Triple-A Colorado Springs and signed Aaron Cook to a minor league contract. Cook, released by the Phillies on Tuesday, is the Rockies' leader in wins, losses and starts.