Abstract: A hydrodynamic approach involving a nonequilibrium equation of state is used in describing heavy-ion collisions at medium and intermediate energies. The double differential cross sections for proton and photon emission in collisions of various nuclei are calculated in developing this approach with allowance for nuclear-viscosity effects and amendments introduced by the microcanonical distribution. The results agree everywhere, including the cumulative region of the spectrum, with available experimental data on the emission of high-energy particles. The approach in question permits reproducing high-momentum distributions of protons from the reaction ¹²С + ⁹Be → p +X at the ¹²C ion energies of 300, 600, 950, and 2000 MeV per nucleon and the energy spectra of hard photons from the reaction ¹²С + ⁹Be → γ + X at the ¹²C ion energies of 2.0 and 3.2 GeV per nucleon.