Mesoporous silica are widely utilised as drug carriers due to their large pore volume and surface area, which facilitate effective loading. Additionally, they can be used to enhance drugs stability and protect against enzymatic degradation due to their silica framework. However, without the addition of a capping material, the loaded cargo may be prematurely released before reaching the target site. This work reports the functionalisation of a commercially available silica microparticle (SYLOID XDP 3050) with stearic acid at various stearic acid loading concentrations (20-120 % w/w). Scanning electron microscopy (SEM) analysis revealed that the pores were capped with stearic acid, with the filling ratio increasing proportionally to the loading concentration. Notably, needle-like structures appeared when the stearic acid amount exceeded 80 % w/w, surpassing the calculated theoretical maximum pore filling ratio (64.32 %). The molecular interactions were highlighted using Fourier-transform infrared spectroscopy (FTIR), as the intensity of the CH