Calcium carbonate nanoparticles and nanorods were synthesized by precipitation from saturated sodium carbonate and calcium nitrate aqueous solutions through co precipitation method. A new route of synthesis was done by using pulse mode feeding of calcium nitrate. The effect of the agitation speed, and the temperature on particle size and morphology were investigated. The formed particles were characterized using X-ray microanalysis, X-ray analysis (XRD) and scanning electron microscopy (SEM). The results indicated that increasing the mixer rotation speed from 3425 to 15,900 rpm facilitates decreasing the average particle size to 64 +/- 7 nm. A rapid nucleation followed by aggregation induced by excessive shear forces phenomena could explain this observation. Moreover, by increasing the reaction temperature, the products were converted from nanoparticles to nanorods. The maximum attainable aspect ratio was 6.23 at temperature of 75 degrees C and rotation speed of 3425. Generally, temperature raise promoted a significant homoepitaxial growth in one direction toward the formation of calcite nanorods. Overall, this study opens a new avenue to control the morphology of the calcium carbonate nanostructures. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.