The paper is focused on the formation of calcium phosphate nanoparticles (CP) in polyelectrolyte-modified microemulsions, in a microemulsion template phase consisting of cyclohexane, water, anionic surfactantant and cosurfactant, in the presence of anionic and cationic polyelectrolyte. It is shown that polyelectrolyte, can be incorporated into the individual inverse microemulsion droplets. The microemulsion droplets and polyelectrolyte-filled microemulsion droplets can be successfully used as a template phase for the nanoparticles formation. Prepared CP in the presence of anionic polyelectrolyte has a different morphology from samples which are synthesized in the presence of cationic polyelectrolyte. Cationic polyelectrolyte(poly diallyl dimethyl ammonium chloride PDADMAC) leads to formation of needle-like CP (10-20 nm in diameter and 100-150 nm in length). Formation of CPat room temperature was confirmed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Size and morphology of the CP samples were characterized using transmission electron microscopy (TEM).