Kaymer, playing flawless golf, took advantage of a rain-softened Pinehurst layout in record style to stretch his U.S. Open lead to a commanding six shots after Friday's second round.
The 29-year-old German, three ahead overnight after opening with a five-under-par 65 that he described as "exceptional", followed up with the same score to post a tournament low 10-under total of 130 in the second major of the season.
Northern Ireland's Rory McIlroy had set the previous lowest score after 36 holes with an aggregate of 131 on the way to a runaway victory in the 2011 U.S. Open at Congressional.
"I don't know what to say," the unflappable but ever-modest Kaymer told reporters after hitting 12 of 14 fairways and reaching 15 of 18 greens in regulation on a challenging par-70 layout. "It's just very, very solid.
"It gets boring, the words that I use, but I mean, there's not much to say. It's just good right now, the way I play golf. I hit some smart shots, I didn't play too aggressive and when I had a good (yardage) number, I went for the flag.
"I didn't three-putt and I made a lot of good putts today and yesterday. You need a little bit of luck here and there, and that has been on my side so far."
Kaymer's six-stroke advantage matched the largest U.S. Open lead after 36 holes, emulating Tiger Woods at Pebble Beach in 2000 and McIlroy in 2011.
When Kaymer concluded his round after teeing off on a sunny but relatively calm morning at Pinehurst, he was eight shots in front of his closest pursuers but, by the time play ended for the day, American Brendon Todd had trimmed that by two.
Todd, who clinched his maiden PGA Tour title at the Byron Nelson Championship four weeks ago, carded a bogey-free 67 in the afternoon to finish alone at four under.
Americans Kevin Na (69) and Brandt Snedeker (68) were a further stroke back but virtually every player in the field will be keeping at least one eye on Kaymer over the weekend as the runaway leader bids to win his second major title.
Kaymer, who gained a major confidence boost from his victory at the elite Players Championship last month, has played brilliant golf at challenging Pinehurst over the last two days.
His opening 65 included six birdies and a lone bogey and the former world number one was error-free on Friday despite having to contend with a few tough pin positions.
With barely a breath of wind on Pinehurst's fabled No. 2 Course which was softened by rain overnight, Kaymer birdied the 10th, 13th and 16th to reach the turn in three-under 32.
Seeking a second major win after landing his first in the 2010 PGA Championship, he picked up further shots at the par-four third and par-five fifth to storm eight ahead of the chasing pack.
"It was pretty awesome," 2011 PGA Championship winner Keegan Bradley said of Kaymer's play after being grouped with the German for the first two rounds at Pinehurst. "He's dialed in. He's as dialed in as I've seen."
World number one Adam Scott, who had struggled with his short game on the way to an opening 73, clawed his way back up the leaderboard with a four-birdie 67 to end the second round at level par, 10 strokes off the pace.
"I needed a good one today," said the Australian. "Hit some good shots and made some putts. It still felt like hard work, but I'm very happy with the score.
"For him (Kaymer) to come out today and back it up (his opening 65) is super. If he does it for two more days, then we're all playing for second spot."
England's Justin Rose, who launched his U.S. Open title defence with a 72, followed up with a 69 for a one-over total.
Phil Mickelson, who has yet to win his national championship where he has been a runner-up a record six times, was a further two strokes back after struggling to a 73, his bid to claim the one major he needs to compete a career grand slam in tatters.
- Sports & Recreation