The aim of this study was the preparation and characterization of calcium titanate- fluor apatite composite nano powder and nano structured bulk. First of all, fluor apatite nano powders were prepared via mechanical alloying. Then, a suspension of 5, 10, and 15 percent by weight of fluor apatite was added to the sol of calcium titanate, and the composite nano powder was prepared via sol-gel method. The characterization of the nano powders was accomplished via X ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) techniques. Researchers have shown that a remarkable suppression of grain growth could be achieved by controlling the sintering temperature and taking advantage of sintering aids during the final stage of a two step sintering (TSS) method. To find how important the temperatures at sintering steps might be, several two step sintering regimes have been conducted. Taguchi experiment design was used to find the best two step sintering cycle, which was consisted of heating for 20 minutes at 1200 degrees centigrade and keeping for 20 hours at 1100 degrees centigrade. The fractional density obtained was higher than 0.97. X ray diffraction and scanning electron microscopy techniques were utilized for phase and structural analysis of the prepared bulks. Fracture toughness was calculated on the basis of microhardness measurements. The composite nano powders and nano structured bulks was soaked in simulated body fluid (SBF) in order to evaluate the bioactivity. pH, calcium, and phosphorous ions release was measured, periodically. Fourier transformed infra-red spectroscopy (FTIR) technique was also utilized to analyze the functional groups of composite nano powders and nano structured bulks after 28 days soaking in simulated body fluid. The grain size of the prepared nano powders and nano structured bulks was smaller than 100 nano meters. Calcium ion increase, phosphorous ion decrease, and presence of apatite functional groups in the remained simulated body fluid showed good bioactivity of the calcium titanate- fluor apatite nano powders and nano structured bulks. The highest fracture toughness was calculated for the composite consisting of 5 percent by weight fluor apatite, equal to 5.98 MPa.m 1/2 . This thesis showed that the calcium titanate- fluor apatite composite nano powders and nano structured bulks would be a desirable substitute for conventional hydroxyapatite for the sake of fracture toughness and bioactivity. Keywords Nano powder, Nano structure, Bulk, Calcium Titanate, Fluor Apatite, Bioactivity, Fracture toughness.