Pseudocapacitive nickel hydroxide was synthesised at particle sizes from around 5–500 nm using hydrothermal methods, with surfactant removed post synthesis using ozone. Syntheses using elctrochemical deposition to produce porous thin films have also been studied. The products have been used to study the depth of charging into the material. Specific capacitance peaked at around 10 nm particle diameter. Further reduction in particle size offered no improvements to specific capacitance, suggesting a depth of charging of 5 nm. Capacitance per unit area was not constant at all particle sizes. This suggests either the anisotropic growth of a more active crystal face or an overestimation of the electroactive surface area for small particles.