Abstract: The invention relates to the use of (A) esters of phosphoric acid and/or partial salts thereof with alkoxylated aliphatic, cycloaliphatic and/or aromatic alcohols and/or (B) fatty acid oligo-dialkanolamides as inhibitors against the formation of incrustations based on organic solids from liquid and/or gaseous hydrocarbon mixtures which are fluid and prone to form such incrustations. Preferred inhibitors having a surface-active character are capable of wetting, and especially of spreading on, solid work material surfaces also in the presence of the fluid hydrocarbon phase. They are particularly suitable as additives to crude oils and/or oil fractions susceptible of forming incrustations.