Most soil formations in arid areas contain problematic soil that may cause construction failure. This research uses geoelectrical resistivity method and geotechnical investigations for Beit Al-Watan area, New Cairo, Egypt For soil detection. Geoelectric investigation has been carried out to determine sub surface lithology in the studied area and hence tracing the distribution of the clay. Then, the boreholes have been drilled nearest to clay location and soil samples have been taken to determine their engineering properties. The vertical electrical sounding (VES) results indicated that the first surface resistivity layer consists of wadi deposits and has resistivity values ranging from 110 to 474.7 Ω.m and has average thickness of 1.5 m. The second geoelectric layer has resistivity values ranging from 31.9 to 842.7 Ω.m and average thickness of 5 m, while the third layer has resistivity values between 67.4 and 454.1 Ω.m and average thickness of 14.4 m, and the fourth layer has resistivity values between 55.4 and 652 Ω.m and its average thickness is 25.2 m. The engineering investigation results reveal that the soil compressive strength has ranged between 1.85 and >4 kg/cm2. The average of liquid limit is 76.8%, the average of plastic limit is 26% and the average of plasticity index is 48.5%. The results of free swell are ranged from 30% to 258% with an average 144%. The study indicates that the clay found at shallow depths and small thickness at southern part, whereas it is deeper and thicker at the northwestern part of the area. Since this soil has high swelling, it must be treated by removing 1.5 meters in thickness and is replaced by suitable materials such as layers of clean graded siliceous sand.