It is demonstrated that the earlier reported superstructure for YNi4B can not accounted for the observed X-ray diffraction patterns. Extra-lines in the diffractograms, which can be related to a superstructure along the c-axis, are evidenced for the first time. The influence of the annealing treatment on the X-ray diffraction patterns has been probed. It results that an inappropriate thermal treatment leads to an average disordered structure characterised by broad Bragg peaks which in first approximation may be explained as due to the CeCo4B-type structure. The high resolution diffraction patterns obtained at the E.S.R.F. evidence an evolution of the superstructure as a function of the Ni content in the Y(Co,Ni)(4)B compounds. The X-ray diffraction measurements performed at the Co and Ni K edges show a dependence of the intensities of the Bragg peaks on the energy of the initial radiation.