Serdobsky District (Russian: Сердо́бский райо́н) is an administrative and municipal district (raion), one of the twenty-seven in Penza Oblast, Russia. It is located in the southwest of the oblast. The area of the district is 1,695 square kilometers (654 sq mi). Its administrative center is the town of Serdobsk. Population: 54,520 (2010 Census); 21,917 (2002 Census); 21,289 (1989 Census). The population of Serdobsk accounts for 64.9% of the district's total population.