[en] Full text: The crystal and magnetic structure of the compound Nd₃Co₂₉Si₄B₁₀ has been investigated by neutron powder diffraction (room temperature and 1.5 K) and Rietveld refinement. The crystal structure has been established as tetragonal (space group P4/nmm) with Nd₃Ni₂₉Si₄B₁₀ structure of lattice constants α = 11.2394(2) Angstroms and c 7.8911(2) Angstroms. AC magnetic susceptibility measurements reveal magnetic transitions at ∼200 K and ∼40 K. The enhanced magnetic diffraction from the neutron diffraction pattern at 1.5 K is consistent with ferromagnetic ordering. The Rietveld refinement indicates that Nd₃Co₂₉Si₄B₁₀ has a commensurate magnetic structure with a magnetic unit cell of the same dimensions as the chemical unit cell. The magnetic ordering at 1.5 K is mainly associated with the rare-earth sites. The magnetic moment of Nd in the 2b site is likely to lie in the basal plane, while the moment of 4d site exhibits a complex structure