Kim, at 23 and bidding for her first major title, was at four under par overall, having opened with a one-under 70 on the East Course at The Broadmoor.
The Korean has enjoyed outstanding success in her last three Open appearances, tying for third in 2008 and 2009 and finishing fourth last year.
Tied for second place at The Broadmoor were Americans Wendy Ward, after 15 holes, first-round leader Stacy Lewis, after 16, and unheralded amateur Amy Anderson, who was yet to tee off in the second round.
Lewis, who won the year's first major and her maiden LPGA Tour title at the Kraft Nabisco Championship in April, held a three-shot lead after seven holes of her second round.
However, she began to self-destruct when play resumed after an hour-long storm delay late on Friday, recording a bogey at the 14th and a double bogey at the 15th.
"I played really good all day," Lewis, who set the first-round pace with a 68, told reporters after parring the 16th before play was suspend in fading light.
"I'm frustrated with the way I finished. It's unfortunate we didn't get done today." Ward had opened with a 73 but she produced bogey-free golf in the second round with four birdies in the first 15 holes before played was halted for the day.
Only 33 players in the field managed to complete the 36 holes, including clubhouse leaders Angela Stanford (70) and fellow American Lizette Salas (73) who both finished at even-par 142.
Paula Creamer, the defending champion, kept herself in the mix after opening with a 72 and was one under for the tournament after 16 holes.
She began the second round by sinking a 30-foot birdie putt at the par-four 10th, her opening hole, and picked up another shot at the driveable par-four second with a lovely chip to within two feet.
However, Taiwan's world number one Yani Tseng, who clinched the LPGA Championship two weeks ago, seemed somewhat out of sorts, particularly with her putting.
Having opened with a 73, Tseng was seven shots off the pace after 16 holes, which included four bogeys and three birdies.
Hawaiian Michelle Wie, who has not finished in the top 10 of a major since 2006, was in serious danger of missing the cut after battling to a 78.
Cristie Kerr, co-leader overnight with compatriot Anderson, returned to the course in the morning for a difficult shot out of a greenside bunker at her 16th hole, the seventh, and was unable able to get up and down to save par.
Kerr also bogeyed the eighth before parring her final hole for a level-par 71. Like the 18-year-old Anderson, she did not start her second round on Friday.
"I won the Open in Pine Needles (in 2007)," world number two Kerr said. "I shot even the first day. It's not a bad omen."
