In many cases, the cis-trans isomers of a compound have different physical properties. These differences can arise due to the difference in the dipole moment of the molecule or due to the difference in the spatial arrangement of atoms. Some of these differences are highlighted below.

• The cis isomer of pent-2-ene has a boiling point of 37^oC but the boiling point of the trans isomer is 36^o The difference is small because the bond polarity is low.
• Due to the polar nature of the bonds in 1,2-dichloroethylene, the boiling point of the cis isomer is 60.3^oC whereas that of the trans isomer is 47.5^oC (the C-Cl dipole moments in the trans isomer cancel each other out).
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• The cis and trans isomers of butenedioic acid display very different reactivities, which can be attributed to the difference in their properties. Maleic acid is the cis isomer and fumaric acid is the trans isomer.
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• Elaidic acid and oleic acid are cis-trans isomers. The former is solid at room temperature (melting point = 43^oC) and the latter is found to be liquid, with a melting point of 13.4^o
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Thus, it can be noted that trans isomers generally have higher melting points than their cis counterparts. They also tend to have lower solubility in solvents that are inert in nature. It has been suggested that the densities of trans isomers tend to be lower than that of cis isomers.

Generally, it can be observed that the individual bond dipole moments in trans isomers cancel each other out since they are on opposite sides. The cis isomers of acyclic systems tend to be less stable than the trans variation, which can be explained by the steric interaction of the substituents.