  Collider processes with identified hadrons in the final state are widely
studied in view of determining details of the proton structure and of
understanding hadronization. Their theory description requires the introduction
of fragmentation functions, which parametrise the transition of a produced
parton into the identified hadron. To compute higher-order perturbative
corrections to these processes requires a subtraction method for infrared
singular configurations. We extend the antenna subtraction method to hadron
fragmentation processes in hadronic collisions up to next-to-next-to-leading
order (NNLO) in QCD by computing the required fragmentation antenna functions
in initial-final kinematics. The integrated antenna functions retain their
dependence on the momentum fractions of the incoming and fragmenting partons.
