Analysis of water soluble ions in PM10 in Pakistan is limited and therefore requires in-depth investigation. In this study composition and sources of ionic profile in PM10 were determined from an urban site of an Asian megacity (Faisalabad) in 2015–2016. The PM10 size fraction sampled on quartz filters was analyzed by ion chromatography for selected inorganic and organic ions. The daily mean PM10 mass concentration was found to be 744 ± 392 μgm−3, exceeding the limits proposed by Pak-EPA (150 μgm−3), US-EPA (150 μgm−3) and WHO (50 μgm−3). The ambient PM10 concentration was found to be highest in winter 2015-16 and autumn 2016, while the lowest in the monsoon 2016. The average total ion concentration was found to be 120 ± 51 μgm−3, which made about 16% of the total PM10 mass. CO32− was the most dominant specie followed by NH4+, Ca2+, K+, NO3−, SO42−, C2O42−, CH3COO−, Na+, Cl− and Mg2+. The ratio analysis of selected ions indicated dominant contribution of biomass burning during autumn and winter and higher impact of fossil fuel burning during spring and summer seasons. Positive Matrix Factorization identified traffic induced soil erosion, biomass burning, fugitive dust from construction activities, secondary aerosol formation processes and fossil fuel emissions from traffic and industry as major sources of particulates. Display omitted •Ions & their sources in PM10 were evaluated from a site in the Indo-Gangetic Plain.•The PM10 values were exceeding the limits fixed by Pak-EPA, US-EPA and WHO.•The total ionic concentration constituted about 16% of the total PM10 mass.•CO32− > NH4+ > Ca2+ > K+ > NO3− > SO42− > C2O42− > CH3CO2− > Na+ > Cl− > Mg2.•Source apportionment was carried out by using PMF model.