A simple and robust capillary zone electrophoresismethod was developed and validated for the determination of amoxicillin and clavulanate, ampicillin, phenoxymethyl penicillin (Pen V) as well as flucloxacillin. Capacitively coupled contactless conductivity detection was employed as detectionmode thatmakes CE a simple and economic tool formoney-constrained laboratories. The developedmethod is straightforward and user-friendly. It offers good sensitivity and sufficient selectivity for the routine assay of the selected penicillins. The repeatabilities were <1.9% RSD for relative peak areas and <1% RSD formigration times for all the analytes. Themethod showed good linearity (R-2>0.995) within the 80-120% range of the target concentration (0.5mg/mL) for each antibiotic. The accuracy of themethod, evaluated by standard fortification at three levels, was good for all the analytes. An extended robustness study was performed by varying +/- 10% of the optimum value of TRIS concentration, l-histidine concentration and temperature in a full factorial design at two levels. This was to evaluate larger than usual variability of factors on the assay value, in order to better cover potential global variance in lab conditions and equipment. Finally, themethod was applied for the determination of percent (%) content of all antibiotics in available formulations.