Nanosized La0.75K0.05Ba0.05Sr0.15MnO3 manganite has been synthesized using sol-gel method. Afterward, the samples were sintered at eight different temperatures ranging from 650 to 1000°C. Phase purity, crystal structure, and the morphology of the sample have been examined using X-Ray Diffractometer (XRD) and Scanning Electron Microscope. It has been found that different higher sintering temperatures significantly affect the phase purity and crystallite size of the sample. Regardless of the sintering temperature, all the samples crystallized in rhombohedral structure with R-3c space group. It was found that the crystallite size is increasing monotonously with sintering temperatures from 41.59 nm up to 73.42 nm. Rietveld refinement analysis from all samples reveals that sintering temperature also affects the average Mn-O bond length (<Mn-O>) and Mn-O-Mn bond angle (<Mn-O-Mn>) of the sample. The average Mn-O bond length is found to increase while the average Mn-O-Mn bond angle tends to decrease as sintering temperature increases. SEM measurement shows that various grain size ranging from ~100 nm up to ~ 350 nm exists in all samples regardless of the sintering temperature.