We study the kinetic freeze-out conditions of hadrons in Au+Au collisions at 11.6 A GeV/c using different parametrizations of an expanding thermal fireball. We take into account the available double differential momentum spectra of a variety of particle species, covering a large fraction of the total momentum space. The overall fit to the data is very good and indicates a relatively low kinetic freeze-out temperature of about 90 MeV with an average transverse expansion velocity at midrapidity of about 0.5 c.PACS numbers: 25.75.Ld, 24.10.Pa When studying the nuclear phase diagram in extreme regions of temperature and density with heavy-ion collisions one is faced with the difficulty that, due to the limited size and strong dynamics of the fireballs created in such collisions, full (global) thermodynamic equilibrium and the thermodynamic (infinite volume) limit can never be reached. The best one can hope for is a state of local thermal equilibrium in a hydrodynamically expanding environment, with thermodynamic homogeneity volumes of several 100 to 1000 fm 3 [1]. If sufficient local equilibration is achieved one can try to extrapolate from the experimental findings to the thermodynamic limit. The most exciting prospect of such an endeavour is the experimental confirmation of a deconfinement phase transition in hot and dense nuclear matter [2].In order to reach this goal an extensive experimental program has been launched studying heavy-ion collisions at various beam energies. The onset of a new phase of nuclear matter would probably be most clearly seen in a study of different observables as functions of beam energy. For this purpose it is necessary to carefully analyze the data at all available beam energies. Here we present a study of the experimental particle spectra from Au+Au collision at a beam momentum of 11.6 A GeV/c measured by several groups [3][4][5] at the Brookhaven AGS. The goal is to find a simple, but realistic parametrization of the freeze-out stage in these collisions. The extracted freezeout parameters, especially the temperature and the mean transverse flow velocity, will be compared with other collision systems and with collisions at different energies. * On leave from Institut für Theoretische Physik, Universität Regensburg; email address: Ulrich.Heinz@cern.chThis should help to understand the gross features of the collision dynamics at ultrarelativistic energies.For the description of particle production we start from the formalism of Cooper and Frye [6] which describes the single-particle spectrum as an integral over a freeze-out hypersurface, thus summing the contributions from all space-time points at which the particles decouple from the fireball:Here g is the degeneracy factor and f (x, p) the momentum distribution at space-time point x. In thermal models one uses for f (x, p) a thermal equilibrium distribution and determines Σ f by a freeze-out criterium for thermal decoupling [7]. For the low temperatures discussed below the Boltzmann approximation is sufficient, but we allow for a...