The ability to manipulate propagation of surface plasmon-polaritons (SPP) on nanostructured surfaces can provide an opportunity to control the optical response of future optoelectronic devices by adjusting their structural parameters. Surface plasmon-polaritons are collective excitations of photons and electrons propagating along a metal-dielectric interface with lifetime of tens of femtoseconds. SPP lifetime in plasmonic nanostructures can be strongly modified with configuration of the structure, type of the metal, and conditions of SPP excitation. Previously it was shown that the time profile of the pulse reflected and transmitted through the nanostructure varies significantly depending on position of resonance on dispersion curves [1]. However, comprehensive studies of dynamics of SPP in nanostructures have not been presented yet, because temporal techniques are quite complex and their results often cannot be interpreted unambiguously. Modification of temporal profile with wavelength can provide new information about optimal conditions of the effective SPP excitation and manipulation. In this paper femtosecond dynamics of resonantly enhanced SPP is studied in planar plasmonic nanostructures. The techniques used for temporal measurements is angular-resolved cross-correlation spectroscopy based on tunable femtosecond Ti:Sapp laser source. The samples are one-dimensional planar metallic grating fabricated from silver films by electron-beam lithography with subwavelength periodicity optimized for excitation SPP in visible spectral range. Fs-scale modification of laser pulse reflected from the sample has been found – change of full width on half maximum (Fig.1a) and shift of maximum position of pulse in time (Fig.1b).figureFigure 1: (a) Spectrum of maximum position shift of femtosecond pulse reflected from plasmonic crystal with excitation of SPP with Fano-resonance profile. (b) Spectrum of FWHM changes of reflected femtosecond pulse. Measurements of fs-scale modification of laser pulse reflected from plasmonic show phase-dependent interplay between two SPP relaxation channels for a single SPP resonance with Fano-type lineshape. This leads to shift of cross-correlation function maximum position up to 40 fs and to narrowing and to broadening of cross-correlation function width depending on wavelength.