260/6 by Sri Lanka (vs Kenya at Johannesburg on 14th September 2007)
It was Sri Lanka’s first game in the ICC World T20 history where they created history by scoring the highest T20I total at that time. After Kenya sent the Asian side to bat first, Sri Lanka scored 260/6 (20 overs) in the first innings.
Though the opener Upul Tharanga scored just 10 runs, another opener Sanath Jayasuriya (88 runs off 44 balls; 11 fours and 4 sixes), skipper Mahela Jayawardene (65 runs off 27 balls; 9 fours and 2 sixes) and the lower-middle-order batsman Jehan Mubarak (46 not out off 13 fours; 3 fours and five sixes) batted furiously to set the record T20I total.
In reply, Kenya were bundled out for just 88 runs (19.3 overs) as Sri Lanka won that match by 172 runs, which was the record margin victory in T20I history at that time.