Purpose: To prepare and characterise doxorubicin nanopatrticles and study their drug delivery in breast cancer.Methods: Doxorubicin nanoparticles were prepared by ionic gelation method using sodium alginate as polymer. The formulations were optimized by cross-linking CaCl2 with sodium alginate at different concentrations. Zeta sizer Nano ZS (UK) was used to determine the mean particle size distribution of the nanoparticle preparations. The shape and external morphologies of the nanoparticles were evaluated by scanning electron microscopy (SEM). Drug release was determined and kinetic release analysis was applied to determine the mechanism of drug release.Results: Entrapment efficiency and mean particle size values were correlated. Scanning electron micrographs showed that the nanoparticles were spherical with little irregularity but without cracks. Doxorubicin release from the sodium alginate nanoparticles followed Korsmeyer-Peppas model which suggest that drug release from the nanoparticles was by diffusion and dissociation from the natural polymer matrix.Conclusion: The doxorubicin-loaded nanoparticles showed concentration-dependent increases in entrapment efficiency. The nanoparticles displayed anticancer properties in breast cancer cell line, thus indicating its potential fo chemotherapeutic application.Keywords: Doxorubicin, Ionic gelation, Nanoparticles, Sodium alginate, Drug release mechanism, Anticance