The reigning British Open champion broke free from what he described as last week's US Open 'torture chamber' at Merion to record an eagle and seven birdies in sauna-like conditions on the Munchen Eichenried course.
Four players, former event winner Martin Kaymer of Germany, Sweden's Alex Noren, England's Matthew Baldwin and Dutchman Robert Jan Derksen share second place on eight under par.
It is Els' lowest round on either the European or PGA Tour since a similar score in the second round of last November's WGC - HSBC Champions event in China.
"It was a very nice round and I haven't shot that number for quite a while," said the South African.
"Today was like walking out of the torture chamber that was last week's US Open and walking onto a nice parkland golf course.
"Of course, you still have to hit the shots but I felt like I was starting to swing the club last weekend at Merion, and I'm lucky enough I could bring it here to Munich.
"But even though I am now leading, it doesn't really matter much until Sunday, but if you get into the race, so to speak, early on in the tournament, it's nice to be right in the hunt."
Els arrived in the Bavarian capital having finished the US Open joint fourth at five over par behind England's Justin Rose.
And over the four rounds at Merion, Els managed 13 birdies but also 14 bogeys and two double bogeys.
The current World No. 20 ranked Els capped his round with a sixth hole eagle that he was playing as his 15th hole by hitting a 245-yard 5-iron from the rough to just six feet.
Els's score is just one shot short of the German course record held by six players.
And Els revealed he will travel to Muirfield in eastern Scotland in the first of a handful of visits before July 18 when he commences the defence of the Open Championship.
It was at Muirfield in 2002 that Els won his first Open crown.
"My good friend, Mr Rupert and I are going up next Tuesday to Muirfield to check it out," said Els.
"So I'll go up every week for the next three weeks and get going with my preparations."
Kaymer delighted a huge hometown crowd in the sweltering conditions and managed to birdie his closing three holes to produce his lowest round in 15 months on either the European or PGA Tour.
"I haven't had a low round now for quite a while, so it's a little bit of a different golf course this week, and there are plenty of birdie chances out there." he said.
Ninety-nine in the 156-player field managed to break par.