At room temperature, it is a white brittle wax, although lower purity samples can be straw coloured liquids.

Dicyclopentadiene is a co-produced in large quantities in the steam cracking of naphtha and gas oils to ethylene.

[3][4] For many years the structure of dicyclopentadiene was thought to feature a cyclobutane ring as the fusion between the two subunits.

[5] The spontaneous dimerization of neat cyclopentadiene at room temperature to form dicyclopentadiene proceeds to around 50% conversion over 24 hours and yields the endo isomer in better than 99:1 ratio as the kinetically favored product (about 150:1 endo:exo at 80 °C).

The reaction is reversible and at room temperature cyclopentadiene dimerizes over the course of hours to re-form dicyclopentadiene.

In accord with the negative values of ΔH° and ΔS° for the Diels–Alder reaction, dissociation of dicyclopentadiene is more thermodynamically favorable at high temperatures.

[13] Hydrogenation of dicyclopentadiene gives tetrahydrodicyclopentadiene (C10H16), which is a component of jet fuel JP-10,[14] and rearranges to adamantane[15][16] with aluminium chloride or acid at elevated temperature.