The Eu3+ activated REInO3 (RE = rare-earth) hosts were composed by the solid state reaction (or ceramic) method. The stoichiometrically calculated phosphor batches were examined by Differantial Thermal Analysis (DTA) and Thermogravimetry (TG) to acquire their thermal behaviors between 50 °C – 1300 °C. The heat treatments were quite long process and needed high temperatures which were at 1000 °C for 10 h and 1500 °C for 12 h. The phase formation of samples were determined by powder X-ray diffraction (XRD) analysis, thus both of samples had similar patterns with single phases in hexagonal type structure. The phosphors particle morphologies and size distributions were analyzed and measured by scanning electron microscopy (SEM). The size distributions includes shredded and dispersed particles with an average diameter between 0.3 μm and 4.2 μm which were directly calculated by the SEM images. The photoluminescence (PL) analysis covering the excitation and emission spectra as well as decay curves (lifetimes) of phosphors were discussed in terms of Eu3+-rare-earth ion doping for both of REInO3 (RE = Er, Sm) type hosts.