The isobaric thermal expansivity alpha p and the isothermal compressibility kappa(T) have been measured at 298.15 K for several nonsaturated hydrocarbons : 1-hexene, 1-hexyne, 1-heptene, 1-heptyne, 1-octene, 1-octyne, o-xylene, m-xylene, p-xylene, and mesitylene (1,3,5-trimethylbenzene). The results, together with previous data from our laboratory, are discussed in terms of the chain length of the hydrocarbons, the degree of unsaturation (-ane, -ene, -yne), the degree of methylation, and the position of the methyl groups on the aromatic ring.