Mikaela Parmlid shot a 64 to finish two shots off the pace while Laura Diaz followed at 7-under-par 65. Defending champion Candie Kung, Suzann Pettersen and Maria Hjorth share fourth place at 5-under-par 67.
Kim played the back side first and hit her third shot out of a bunker to 5 feet for a birdie at the par-5 12th. She then sank a 20-foot putt for a birdie at the 13th and kept on rolling with a birdie at the par-4 14th after her approach stopped within 3 feet of the hole.
The 20-year-old two-putted for a birdie at the par-5 15th to make it four in a row and ran home a 12-footer for a birdie at the 18th to make the turn at 5 under.
She continued her fine play on the greens on the front nine and drained a 25-foot putt for a birdie at the par-4 first. Kim added a birdie at the fourth but found trouble with a bogey at the par-3 fifth after an errant tee shot.
Kim responded in fine fashion with a birdie at the sixth and hit a 6-iron to 7 feet for a birdie at the par-3 seventh. Kim then converted a 15-foot putt for a birdie at the eighth and dropped her second shot inside 3 feet at the par-4 ninth.
Kim rolled in the short birdie putt to match the course record.
'It still hasn't sunk in, but it fills my heart with joy and all that jazz, knowing I had a great round,' said Kim, who also shot a 62 at last year's Welch's /Fry's Championship. 'I think I'm more business-like now, and I'm very pleased with myself, but I don't want to put myself up too high.'
Kim, who enjoyed a steady rookie campaign in 2003, has been finding herself near the top of the leaderboard more often this year, including last week in Pennsylvania when she tied for sixth.
'This is a 72-hole event, so I was focusing on one shot at a time,' said Kim. 'This week and last week, that's what I've focused on. I'm still young and like to think ahead.'
Parmlid tallied four birdies on the front nine and picked up back-to-back birdies starting at the par-3 11th. The 23-year-old added a birdie at the 15th and hit a 6-iron to 15 feet for a birdie at the last.
'I was just taking one shot at a time and had a lot of fun,' said Parmlid. 'I didn't really look ahead and just saw the opportunities all day.'
Diaz played alongside Kim on Thursday and collected four birdies and a bogey over her first nine holes. She managed to keep pace with Kim on the front side with back-to-back birdies from the first and a birdie at the fourth before a bogey at the fifth dropped her back to minus-5.
The 29-year-old countered with a birdie at the seventh and closed with a birdie at the ninth.