The present study focuses in situ and laboratory determination of geotechnical parameters of soil samples from the Niamey region (Niger). The collected soil samples were analyzed at the geotechnical laboratory (GEO-LAB CONSULT). Petrographic analysis of samples from manual wells showed three stratas of varying thickness. From top to bottom, these are: medium to coarse yellowish-red sand (50 to 80 centimeters), lateritic gravel (20 to 40 centimeters) and ferruginous armour (40 to 60 centimeters). The obtained results from the penetrometer boreholes were used to determine the depth of the foundations, the thickness of the studied stratas and the ultimate stress of the soil for foundations dimensioning. At the Aeroport site, the depth of the lowest point is 1.5 meter, with an ultimate stress of 5.05 bars. The Satu site has a lowest depth point of one meter, with an ultimate stress of 7.47 bar. The Kalley Plateau site gave a lowest depth point of 1.5 meters with an ultimate stress of 2.20 bars, and the Saguia Béné site had a lowest depth point of 1.5 meter with an ultimate stress of 2.15 bars. Analysis of the water content of studied soils, combined with the penetrometric results, shows that water content influences soil strength.