Graphene Oxide is the oxidized form of graphene produced by oxidizing crystal graphite with a mixture of sulfuric acid, sodium nitrate, and potassium permanganate (the Hummers method). Structurally, Graphene Oxide can be visualized as a graphene sheet with its basal plane decorated by oxygen-containing groups. Due to high affinity to water molecules by these groups, Graphene Oxide is hydrophilic and can be dissolved in water. The solubility in water makes the deposition of the thin films of the Graphene Oxide straightforward. Graphene Oxide is a poor conductor but its treatment by light, heat, or chemical reduction can restore most properties of pristine graphene.