H. Hopf showed that the only constant mean curvature sphere S2 immersed in R3 is the round sphere. The K¨ahler framework
is an adequate approach to generalize Hopf’ s theorem to higher dimensions. When ϕ : M → Rn is an isometric immersion from
a K¨ahler manifold, the complexified second fundamental form α splits according to types. The (1, 1) part of the second fundamental
form plays the role of the mean curvature for surfaces and will be called the pluri-mean curvature pmc. Therefore isometric
immersions with parallel pluri-mean curvature (ppmc isometric immersions) generalize in a natural way the cmc immersions. It
is a standard fact that R8 is the smallest space where CP2 can be embedded. The aim of this work is to generalize Hopf’s theorem
proving in particular that the only ppmc isometric immersion from CP2 into R8 is the standard immersion.