Lateritic soils are used as the construction of road sub-base materials. Some lateritic soil does not satisfy the sub-base specifications recommended by Ethiopia Road Authority (ERA). This research was focused on Wogelsa, Kebele 14, and Zenzelima lateritic soil, which does not satisfy the sub-base material specifications in the ERA manual. Thus, in this study blending of lateritic soils with cinder gravels (Wogelsa, Debankie, and Zenzelima), was used to improve the strength and quality of sub-base material. The improved materials exist in an unsaturated state. Then SWCC curve of each blended material was determined to investigate the unsaturated properties of lateritic soil blended with cinder. To achieve these goals experimental tests were carried out in three phases. Such as in the 1 st phase, natural lateritic soil and cinder properties. In the 2 nd phase, the properties of the blended sample were studied. In this phase Wogelsa cinder gravel blended with Wogelsa lateritic soils in the trial proportions of 10 to 75% of cinder, 60 to 75% of cinder by weight was done for both Keble 14 and Zenzelima lateritic soils blended with Debankie and Zenzelima cinders respectively. The Atterberg limit, gradation, compaction, and California Bearing ratio were used to check the ERA specification. From the laboratory result, the sub-base specification was satisfied at 75% cinder and 25% lateritic soil for all locations. In the 3 rd phase, the soil water characteristics curve (SWCC) was developed for the blended specimen and natural lateritic soil using pressure plate apparatus. The laboratory-measured data points were curve-fitted based on Fredlund and Xing's (1994) fitting model. SWCC results are used to interpret the lateritic soils blended with cinders. The air entry value of the blended specimen was high at 70% cinder and 30% in all lateritic soils of the study. Because the density of the specimen increased as the cinder increased to 70% and the surface-to-surface contact of the blended specimens increased and the void space of the cinder was fully occupied by the fine lateritic soils. Key words: SWCC, blended sample, lateritic, cinder, CBR, Compaction, index properties