It was Jayasurya from Srilanka had hit 11 sixes in one ODI Innings and later on Afridi from Pakistan had 11 sixes against Srilanks in 1996. I hope, the question is not about "most sixes in an ODI", but is about most sixes in ODI. As on 16-Mar-2011, it is Shahid Afridi (Pakistan) who hit 289 sixes so far! He is followed by Sanath Jayasuria (Sri Lanka)---270 sixes and Sachin Tendulkar (India)---193 sixes.
Shahid Afridi of pakistan,BOOM BOOM, pakistan's ODI & T20 captain.
293 sixes in odi
286 sixes hits sachin in ODI .
Most sixes by a team in an ODI innings?
166 sixes in odi
V Sehwag has played 196 and has hit 96 sixes as at 15th Dec 2008.