The effect of ammonium fluoride (NH4F) concentration on the dimensions (length, diameter, and wall thickness) of the self-organized nanotube arrays has been investigated. Results show that varying the concentration of NH4F exerts a strong effect on changing the dimensions of the as-grown nanotube arrays. The length of the nanotube arrays increases gradually by increasing the concentration up to a maximum length at a concentration of 1.00 wt%, after which the length decreases slightly with the increase in NH4F concentration. It was also observed that the diameter and wall thickness of the nanotube arrays vary with the change in concentration of NH4F, where the diameter was found to alter between 80 and 140 nm, and the wall thickness decreases by increasing the NH4F concentration. These results indicate that it is possible to entirely control the dimensions of the nanotube arrays, by tailoring the concentration of NH4F besides the anodization time and voltage.