This Letter reports a measurement of the cross section of prompt isolated photon pair production in pp
collisions at a total energy ffisffiffi
¼ 1:96 TeV using data of 5:36 fb1 integrated luminosity collected with
the CDF II detector at the Fermilab Tevatron. The measured cross section, differential in basic kinematic
variables, is compared with three perturbative QCD predictions, a leading order parton shower calculation
and two next-to-leading order calculations.