Mineral changes of Philippine and Indonesia nickel lateritic ores during the sintering and the mineralogy of their sinter were studied in present work. A laboratory scale sintering pot was used to prepare the sinter samples. Thermo-gravimetric (TG) tests, differential thermal analysis (DTA), and X-ray diffraction (XRD) experiments were carried out to understand the mineral change of laterites. These measurements indicate that chlorite (Fe,Mg,Al)₃(Si,Al)₂O₅(OH)₄ and serpentine Mg₂₁Si₂O₂₈(OH)₃₄H₂O are the primary phases, while FeO(OH) and (Fe,Mg,)₃Si₄O₁₀(OH)₂ are the minor phases in both Philippine and Indonesia nickel laterite. The XRD, scanning electron microscope (SEM), and energy dispersive spectrometer (EDS) were used to analyze the sinter samples; the results demonstrate that olivine (Mg,Fe)₂SiO₄ is the main bonding phase in both Philippine and Indonesia laterite sinters, and spinel MgFe₂O₄ is also found as the solid bonding phase in the Philippine laterite sinter.