Nanoparticles of mesoporous MCM-41 silica were synthesized, functionalized by 8-20% of hexamethylenetetramine (HMT) and employed as effective drug carriers. The carriers’ mesopores were filled with the cyclophosphamide (CP) anticancer medicine. The pore size, pore volume and surface area of pure MCM-41 were obtained equal to 32.54 Å, 0.89 cm³/g and 996.84 m²/g but they were noticeably decreased for the HMT-functionalized MCM-41 materials approving the HMT molecules were bound onto the surfaces and pores of such samples. The release of drug was performed in three neutral PBS, alkaline and acidic solutions. A sharply enhanced CP release was observed in approximately 24 h (burst release) while subsequently release of the drug was gradually boosted within 7 days indicating a sustained release behavior. The maximum drug release amount was measured in alkaline medium, moderate quantity in neutral solution and minimum value in acidic environment. The kinetic of the drug release was examined using the Korsmeyer-Peppas, Hixson-Crowel, Higuchi, first-order, and zero-order models and it was revealed that the CP release from the nanocarriers obeyed the Korsmeyer-Peppas model. Finally, it was decided that the MCM-41 sample containing 14% HMT was the most appropriate system as it had high/favorable quantities of drug loading plus drug release.