A composition for forming a radiation absorbing coating which comprises an organic solvent, a radiation absorbing polymer or a radiation absorbing material dissolved therein and a crosslinking agent having blocked isocyanate groups. Since the isocyanate groups of the crosslinking agent have been blocked, the composition containing the crosslinking agent has excellent storage stability. When the composition applied to a substrate and then baked, crosslinking proceeds to give an antireflective coating, which does not intermix with a resist layer to be formed thereon by coating and is free from diffusion of a photo-generated acid thereinto from the resist layer. As a result, a resist image free from footing or scum can be formed.