To investigate the depth of charging at the material surface, batches of nickel hydroxide nanoparticles were hydrothermally synthesised in the range 3–450 nm. Any surfactant added was removed post synthesis using ozone. The capacity per gram (Cs) increased and the capacity per unit area (CA) was constant with decreasing particle size down to 20 nm. Further reduction in particle size resulted in a decrease in both CS and CA, suggesting the Ni(OH)2 is charged to a depth in the order of 10 nm at the charging rate studied. The results obtained have implications in the design of Ni(OH)2 electrodes in charge storage applications.