Context : NGC404 is a nearly face-on nearby low-luminosity lenticular galaxy .
Probing its characteristics provides a wealth of information on the details of possible evolution processes of dS0 galaxies which may not be possible in other , more distant objects .

Aims : We study the internal kinematics and the spatial distribution of the star formation history in NGC404 .

Methods : We obtained long slit spectroscopy at the OHP 1m93 telescope along the major and minor axes of NGC404 .
The spectra have a resolution R = 3600 covering a wavelength range from 4600 to 5500 Å .
The data are fitted against the Pegase.HR stellar population models to derive simultaneously the internal stellar kinematics , ages and metallicities .
All this is done while taking into account any instrumental contamination to the line of sight velocity distribution .
Firstly , the global properties of the galaxy are analyzed by fitting a single model and to the data and looking at the kinematic variations and SSP equivalent age and metallicities as a function of radius .
Afterwards , the stellar populations are decomposed into 4 components that are individually analyzed .

Results : NGC404 clearly shows two radial velocity inversions along its major axis .
The kinematically decoupled core rotates in the same direction as the neutral hydrogen shell that surrounds the galaxy .
We resolved the star formation history in the core of the galaxy ino 4 events : A very young ( < 150 Myr , and [ Fe/H ] = 0.4 ) component with constant on-going star formation , a second young ( 430 Myr ) component with [ Fe/H ] = 0.1 , an intermediate population ( 1.7 Gyr ) which has [ Fe/H ] = -0.05 and , finally , an old ( 12 Gyr ) component with [ Fe/H ] = -1.26 .
The two young components fade very quickly with radius , leaving only the intermediate and old population at a radius of 25″ ( 370 pc ) from the centre .

Conclusions : We conclude that NGC404 had a spiral morphology about 1 Gyr ago and that one or many merger events has triggered a morphological transition .
The interstellar medium in the galaxy has two components , the cold molecular gas is most probably a remnant from its past spiral incarnation and the outer neutral hydrogen layer which has probably been acquired in one of the latest merger .