A cross sectional study was carried out at Kality wastewater stabilization ponds, inrnAddis Ababa from 4 may to 24 August 2009. The objective of the study was to evaluaternthe performance of the stabilization ponds and to assess the physico-chemicalrncharacteristics of the sludge. The plant comprised of facultative and maturation ponds inrntwo series.rnAccordingly, Samples were taken from the influent, two facultative ponds effluent, lastrntwo polishing ponds effluent and the final effluent while sludge samples were taken fromrnfour piles of drying beds. Laboratory analysis was carried out following standardrnmethods for the analysis of temperature, pH, conductivity, DO, BOD5, COD, TDS, TSS,rnS2-, SO4rn2-, TN, NH4rn+-N, NO3rn--N, orthophosphate, TP, Total Coliforms, Fecal Coliforms,rnCr, Pb, and Cd and for the sludge pH, moisture content, volatile matter, fixed carbon,rnash, nitrogen (NO3rn--N), total phosphorous (TP), potassium (TK), Pb, Cd, Cr.rnResults of this study showed that the average concentrations of BOD5, COD, TSS andrnTDS in the influent and final effluent were 290.1, 585.8, 212, 328.3; and 47.5, 131.4,rn71.0, 294.7 mg/L respectively, with the removal efficiency of 83.6%, 77.6%, 66.5% andrn10.3% respectively. The concentrations of NH4rn+- N, NO3rn- N, TN, Ortho-P and TP werern30.7, 1.13, 89.8, 11.7 and 14.6 mg/L respectively in the effluent and for the effluent theirrnrespective concentrations were found to be 16.2, 0.30, 37.3, 8.4 and 10.2 mg/l. Thernremoval efficiency of the pond system for these parameters were 47.3% for NH4rn+- N ,rn73.5% for NO3rn- N, 58.5% for TN, 28.0% for Ortho-P and 30.1% for TP. Thernconcentrations of NH4rn+- N, NO3rn- N, and TN were below the provisional dischargernstandards. But the concentration of total phosphorous was found to be slightly higher thanrnthe provisional discharge standards, which indicates the possibility of eutrophication inrnthe receiving water body (little Akaki river). The reduction percentage of S2- was 96.3%rnand 66.2% for SO4rn2-.rnOn the other hand, the reduction percentages of Total Coliform (TC) and Faecal Coliformrnwere 99.40 and 99.76 respectively, although the concentration in the final effluent wasrnvery high; 3.4Ã—108 MPN / 100 ml and 2.7Ã—107 MPN / 100 ml respectively.rnRegarding the physico-chemical properties of the sludge, its average pH was 6.58Â± 0.11rnand the percentage of total phosphorous, total potassium and NO3rn--N were 3.66 Â± 0.38 %,rn0.70 Â± 0.08% and 0.04Â± 0.01% respectively, while the concentration of heavy metalsrn(Cd, Cr, and Pb) was less than 20 mg/L in all samples.rnBased on the results of the study, the waste stabilization ponds system was found to bernefficient in removing most of the pollutants of concern. But it is recommended to usernfurther treatment options to remove TC, FC, total suspended solids and total phosphorousrnprior to discharge or reclaim the wastewater.