Biosolids can be used as nutrient sources in agricultural and horticultural areas. The objectives was to chemically characterize the materials relative to their nutritional value and potential toxic environmental impact and determine the mineralization rates of the materials relative to their ability to supply nutritional fertility. The materials used in this study were: Limed Slurry, Limed Cake, Black Kow, Black Hen, Disney Compost, Milorganite, N-Viro and Baltimore Pellets. All materials were characterized for N, P, K, Ca, Mg, Fe, Mn and heavy metals (Cd, Zn, Cu, Pb, Mo and As) using four repetitions. Milorganite contained the highest N content followed by Black hen and Baltimore pellets. Limed slurry contained more than 2% N and P; Limed Cake, Limed Slurry and N-Viro had adequate amounts of Ca while all the sources had adequate amounts of Mg. Milorganite and baltimore pellets contained the highest levels of Fe (39500 and 39000 ppm respectively) while baltimore and black hen had the largest amount of Mn (850 and 550 respectively). All the biosolids tested contained low heavy metals concentrations. For the mineralization study, the materials (90Kg/ha and 180Kg/ha), were mixed with an uncoated white sand and a surface layer of Arredondo fine sand and placed into incubation lysimeters. A CO2 trap of 1N NaOH was placed in the head space of the lysimeters to estimate microbial decomposition rate. Limed slurry had the highest percent mineralization at both rates, followed by Milorganite and Baltimore pellets. Based on CO2 evolved, microbial activity appeared to be occurring. Biosolids appear to have satisfactory nutritional values and mineralization rates.