This paper described the covalent attachment method to immobilize Deoxyribonucleic acid (DNA) sequences on surface of DNA sensor which was used to determine herbicide tolerance transgenic of soybean. The probe sequence was (5’GCCATCGTTGAAGATGCCTCTGCC-3’) which can hybridize with the CaMV 35S promoter of Roundup Ready soybean that was attached onto the surface of sensor by means of 3-AminoPropyl Triethoxy-Silane (APTS). The DNA sequence bindings were identified by the FTIR spectra. The morphology of attached – DNA sequences onto that was investigated by atomic force microscopy (AFM). The sensitivity of sensor was found, in this work, . Temperature effect on the hybridization process was also described. | DNA covalent attachment on conductometric biosensor for modified genetic soybean detection