Cook and Hales, a debutant, will open the batting for the hosts against India in their five-match one-day international series starting in Bristol on Monday.
Ranked fifth in the ICC rankings, England will be hoping to begin their journey to the 2015 ICC World Cup in Australia with some winning form against the second-ranked Indians.
Cook, who has not made a century in his past 35 ODIs, said he will continue to bat as he prefers, alongside the big-hitting Hales.
"I don't think it changes my role," the England skipper said.
"The job of the top four or five is to try and score a hundred, and [to] win the game by setting up the game.
"You have to try and do it in your way. What's pleasing about Alex over the last month or so is that he has scored four centuries for Nottinghamshire and at a good rate too.
"He is a different batter to the other guys - he hits the ball incredibly hard, in different areas, with an unorthodox technique.
"He's done really well in T20 cricket and he's got the opportunity over these five games to show us what he can do over 50 overs."
Cook confirmed former opening partner Ian Bell would bat at three, although nothing was in concrete six months out from the World Cup, starting in February.
"He will bat at three. So there is a different role for Ian to play," Cook said of Bell, a veteran of 146 ODIs.
"I have no doubts that he can do that and also if we want to change it back at the top of the order, we can.
"The partnership between Belly and me has been a good one over the last couple of years."