Longest chess game possible (maximum moves) What is the longest chess game possible in terms of chess moves? I read somewhere that there is a theoretical maximum of 5949 moves. But I don't see any proof and I don't think it is correct. 

Can it be infinite? 

Source
Some cleaning up is required, I think:

The number on the website you link to differs from the results published in     Bonsdorff et al., Schach und Zahl. Unterhaltsame Schachmathematik. pp. 11–13.
There they say that if the 50-move-rule is mandatory the longest possible game (i.e. where both players cooperate to achieve the weird goal of a game of maximal duration) lasts 5899 moves.
Possibly, the web site used a simpler upper estimate for the "gaps" between pawn moves and captures that cannot be achieved in all occasions.

However, the 50-move-rule (and also the position-repeated-three-times-rule) is not mandatory, i.e. whether or not a player demands remis by that rule is up to him! The players may decide to ignore the rule and play on, thus allowing for an eventually periodic sequence of moves, i.e. an infinite game.