  Mueller Navelet jets were proposed 25 years ago as a decisive test of BFKL
dynamics at hadron colliders. We here present the first next-to-leading BFKL
study of the cross section and azimuthal decorrelation of these jets. This
includes both next-to-leading corrections to the Green's function and
next-to-leading corrections to the Mueller Navelet vertices. The obtained
results for standard observables proposed for studies of Mueller Navelet jets
show that both sources of corrections are of equal and big importance for final
magnitude and behavior of observables, in particular for the LHC kinematics
investigated here in detail. Our analysis reveals that the observables obtained
within the complete next-to-leading order BFKL framework of the present work
are quite similar to the same observables obtained within next-to-leading
logarithm DGLAP type treatment. There is still a noticeable difference in both
treatments for the ratio of the azimuthal angular moments < cos (2 phi) > / <
cos phi >.
