We study the problem of evolution of a density pulse of one-dimensional interacting fermions with a non-linear single-particle spectrum. We show that, despite non-Fermi-liquid nature of the problem, non-equilibrium phenomena can be described in terms of a kinetic equation for certain quasiparticles related to the original fermions by a non-linear transformation which decouples the left-and right-moving excitations. Employing this approach, we investigate the kinetics of the phase space distribution of the quasiparticles and thus determine the time evolution of the density pulse. This allows us to explore a crossover from the essentially free-fermion evolution for weak or short-range interaction to hydrodynamics emerging in the case of sufficiently strong, long-range interaction.PACS numbers: 73.21.Hb, 73.22.Lp, 47.37.+q Understanding non-equilibrium phenomena is one of central themes in condensed matter physics. For Fermiliquid systems (e.g. electrons in metals) such phenomena are conventionally described in the framework of a quantum kinetic equation for quasiparticle excitations. According to Landau Fermi-liquid theory, it has the same form as for weakly interacting particles up to a renormalization of parameters (effective mass, interaction constants, and scattering integral). This equation governs the evolution of a single-particle density matrix (characterizing the quasiparticle phase space distribution) and readily yields various physical observables 1-3 .For a variety of strongly interacting fermionic systems, the Fermi liquid theory (at least, in its standard form) is not applicable: interaction destroys the quasiparticle pole. In these cases on has to find an alternative way to describe transport and non-equilibrium phenomena. This is usually done by formulating effective theories in terms of some collective degrees of freedom. A famous realization of a non-Fermi-liquid state is provided by one-dimensional (1D) interacting fermions. This system is characterized by a strongly correlated ground state-Luttinger liquid (LL) 4-8 -which exhibits an infrared divergence of an electronic self-energy, eliminating the quasiparticle pole from the spectral function. This manifests itself in a power-law suppression of the tunneling (zero-bias anomaly) and indicates that quasiparticle excitations are ill-defined. A well-known tool for dealing with such correlated 1D systems is bosonization 4-8 . After linearization of the fermionic spectrum, it allows one to map the problem onto one of non-interacting bosons. For arbitrary distribution functions, the non-equilibrium bosonization yields results for LL correlation functions in terms of singular Fredholm determinants 9,10 .In this work we explore kinetics of interacting 1D fermions, having in mind the following model setup. Initially, a hump (or a dip) in a fermionic density is created by an external potential. At time t = 0 the potential is switched off, and electronic pulses start to propagate to the right and to the left. The evolution of the electronic density as...