Heavy water is used for slowing down the speed of neutrons in nuclear reactors, hence used as moderator. Boiling point of heavy water is greater (374.42 K) than that of ordinary water (373 K), hence heavy water is more associated. Dielectric constant of ordinary water is greater than that of heavy water, hence ordinary water is a better solvent.

In H₂O₂ , the O–H groups are not in the same plane. So it has non-planar structure. It has a half-opened book structure in which the two O–H groups lie on the two pages of the book. The angle between two pages of the book is 94^o and H–O–O bond angle is 97^o.