A reversed phase high performance liquid chromatographic method has been developed for the simultaneous determination of cefaclor and ceftriaxone cephalosporin antibiotic. The developed method has been validated and applied to mixtures of the commercial formulation and spiked human plasma. A mediterranea C18 column (4.6 × 250 mm) was used with isocratic solvent delivery system and UV-visible detector. Different experimental parameters like solvent composition (acetonitrile: methanol: triethyl amine buffer 1:1:2 (v/v), flow rate of mobile phase (0.6 mLmin-1), pH of the buffer (7), and wavelength (260 nm) were optimized for effective separation and esolution of the analyte peaks. The separation was achieved in 6 min with retention times of 4.94 ± 0.056 min and 3.39 ± 0.022 min for cefaclor and ceftriaxone respectively. The linear range for both the studied drugs was found to be 0.5-250 μgmL-1 with r2 of 0.9987 (cefaclor) and 0.9997 (ceftriaxone). The limit of detection (3.3 σ/S) was found to be 2.34 × 10-2 μgmL−1 and 1.70 × 10−2 μgmL-1, respectively, for cefaclor and ceftriaxone. Similarly limit of quantification (10σ/S) was 7.10 × 10−2 μgmL-1 for cefaclor and 5.15 × 10−2 μgmL-1 for ceftriaxone. The chromatographic procedure was applied to commercial formulations and spiked human plasma and the results were compared with literature HPLC method.