Knowledge of basement relief, overburden thickness and depth to different sedimentary units within the Chad basin are essential information for geothermal studies and update of geologic information of the basin. This study entails the interpretation of twenty seismic profiles with focus on the key marker horizon separating the major sedimentary sequences of Nigeria sector of the Chad basin to deduce the depth to the Cenozoic unconformity and base of Cretaceous/top of the Basement complex. The results of this work showed that depth to the Cenozoic unconformity range from about 100m b.g.l. around southern outskirts of the Basin to about 1700m b.g.l. around Lake Chad. In the middle of the study area around Gubio, a depth of 800m b.g.l. was obtained and in the depression between Maiduguri and Bida is was found to be 1100m b.g.l.. The depth to base of Cretaceous/top of Basement in this study was found to range between 500m b.g.l. to 6500m b.g.l. north of Maiduguri and 5000m b.g.l. around Gubio area which indicate thickness less than 8000m and 10000m as reported by earlier works on the basin.