The use as a resist material of a methanofullerene derivative having a plurality of open-ended addends, and to a method for forming a patterned resist layer on a substrate using the methanofullerene derivatives. The methanofullerene derivatives can be represented by the formal C2x(CR1R2)m where x is at least 10, m is at least 2, each addend represented by CR1R2 is the same or different, and wherein each R1 and R2 is each a monovalent organic group, or a divalent organic group which forms a ring structure by being joined to the fullerene shell, or where both R1 and R2 of an addend are divalent groups, they may be mutually joined to form a ring structure, save that at least two of R1 or two of R2 are monovalent, or a mixture of such derivatives. The use of any methanofullerene derivative which has been chemically amplified for formation of a patterned resist layer. The essential step of the method is forming a coating layer comprising the methanofullerene derivative on the substrate surface, the methanofullerene derivative being chemically amplified by including in the coating layer at least one additional component which increases the sensitivity of the exposed layer to actinic radiation which is subsequently used to pattern the layer.