Abstract: The invention relates to a process for nanostructuring the surface of a solid material in order to form a regular pattern of nanostructures on said surface, comprising: irradiating the surface by a plurality of pulse trains (20) of a femtosecond laser beam: each pulse train (20) comprises at least two pulses (21, 22), each pulse has a peak fluence, and a sum of the peak fluences of the pulses of a pulse train is between 10% and 70% of a threshold fluence corresponding to a material ablation threshold for one pulse for said material, two consecutive pulses of a pulse train are separated by a peak-to-peak duration ?T between 500 fs and 150 ps, two consecutive pulse trains are separated by a duration greater than 10 ?T, obtaining a regular pattern of nanostructures on said portion of surface, having a spatial periodicity lower than 130 nm.