As par t of a program to det ermine acc urat ely t he heat s of combustion of speciali zed fuels in the kerose ne range, seve n hydrocarbons, biphenyl, bicyclohexyl, cyclohexylbenze lle, n-hexylbe nzene, n-hexylcyclohexa ne, l -cyclope nty lheptane, a nd n-dodecane were sy nthesize d or purified from co mmercial mate ri a l. Physical co nstants were det ermined on the purified samples. These materials may have use as seco ndary stan da rds for heat of co mbu stion meas urem ents.