The porous silicon (pSi) materials have been shown to possess properties that make them ideal for hydrogen storage applications, however, these materials have not yet been studied in-depth. Thus, this project aims to optimise the pSi thin film from Si wafer and pSi powder from Al-Si Alloy using acid etching techniques that would improve their morphologies, compositions, and hydrogen storage performance. The morphology of the pSi thin film revealed a uniformly distributed mesoporous structure, with film thickness of about 32 micrometres. It was activated at 150 degrees Celsius, and the Pressure-Composition-Isotherm results showed significant hydrogen absorption of 8 wt.% at 150 degrees Celsius and 0 to 37 MPa pressure. This work also contributes to the understanding of the gas desorption behaviour of as-fabricated pSi thin film. This study examined the reduction of the lattice spacing associated with the desorption of gases stored within the as-fabricated pSi crystal lattice using in-situ X-Ray diffraction measurements. Also, temperature-programmed desorption, thermogravimetric analysis, and time-of-flight secondary ion mass spectrometry analytical techniques were employed to analyse the gaseous elements (H, F, O, and C) present in the pSi layer, and it was found that gases effectively desorb at 500 degrees Celsius. Consequently, the pSi thin film was activated at 500 degrees Celsius which resulted in an even higher hydrogen absorption of 8.5 wt%. In addition, the hydrogen storage capability of pSi powder produced from Al-Si alloy was discovered for the first time in this study, and the hydrogen storage properties of the pSi powder were further investigated. Double acid etching and nickel blending of the pSi powder resulted in 0.81 wt.% hydrogen absorption capacity. It was also found that the optimum hydrogen storage performance of the pSi powder was obtained at 250 degrees Celsius and 350 degrees Celsius, which indicates that the main reaction mechanism between the pSi powder and hydrogen could be chemisorption. Also, both the pSi thin film and powder showed promising durability after consecutive hydrogen charging and discharging cycles. Therefore, this study provides new experimental knowledge and a fundamental understanding on the fabrication processes, morphologies, compositions, and interactions with hydrogen of pSi materials, and their potential as hydrogen storages.