Many of the current chemotherapeutic drugs cause severe toxicity to the body, such as hair loss and nausea, when administered at high systemic doses. The objective of this project is to study the use of biocompatible mesoporous silica particles as vehicles for the local and sustained delivery of a chemotherapeutic agent: Doxorubicin (Dox). A sulfonic acid-functionalized mesoporous silicate (SBA-SO3H) was prepared in a one-step process. The sulfonic acid protons were exchanged for Na+ ions to increase the drug loading capacity of the silicate particles. The resulting material (SBA-SO3Na) was characterized by FT-IR, thermogravimetric analysis, and its porosity, surface area and particle size were determined. Doxorubicin was incorporated in SBA-SO3Na through an ion-exchange process in which the Na+ ions of the solid were replaced by DoxH+. An average drug loading of 85.2 wt% was achieved at a 4:1 solid to drug weight ratio. The release profile of doxorubicin at 37°C was monitored by UV-Visible Spectroscopy in 0.5wt% NaCl/0.08wt% CaCl2 aqueous solutions. An average of 81.3 wt% of the loaded Dox was released over a six-day period. Preliminary tests measuring the cytotoxicity of Dox-loaded SBA-SO3 particles onto 4T1 murine cancer cells line have been conducted.