Abstract: A lubricant composition is disclosed that comprises: (a) a lubricant and (b) at least one molybdenum-containing compound in the form of surface-capped nanosized particles of the general formula: (Z)n(X—R)m wherein Z is an inorganic moiety comprising molybdenum and sulfur in the form of particles having dimensions in the range of from about 1 to about 100 nm; (X—R) is a surface-capping reagent wherein R is a C4 to C20 straight or branched-chain alkyl or alkylated cycloalkyl radical or radicals and X is a functional group capable of specific sorption and/or chemical interaction with molybdenum/sulfur moiety; n is the number of molecules of Z in the particles; m is an integer representing the amount of surface-capping reagents relative to a single particle; and the ratio of m to n is in the range of from about 1:1 to about 10:1.