  We review recent results on hard observables in p+p, d+A and A+A collisions
obtained by the PHENIX experiment. Emphasis is put on those measurements that
provide insight into the properties of hot QCD media expected to be created in
nucleus-nucleus collisions at RHIC energies. Direct photon spectra, jet
properties and heavy quarks production measured in p+p and d+Au collisions are
compared to the same observables extracted in heavy ion collisions to find
modifications due to the presence of hot QCD matter.
