In this study, the compostability of treatment sludge sourced from the food industry (TS) and cattle manure (CM) was investigated. For this purpose, sunflower stalks (SS) were added as a bulking agent and composting experiments were performed. Different mixtures (R-1, R-2, R-3) were prepared in order to determine the individual and co-compostability of the raw materials used. In the R-1 reactor, TS and SS in the ratio of 70:30, in the R-2 reactor, CM and SS in the ratio of 70:30, and in the R-3 reactor, TS, CM and SS in the ratio of 35:35:30 were mixed, respectively. Temperature, organic matter, pH, electrical conductivity (EC) and C/N ratio parameters were monitored during the 21 -day process. The highest temperatures during the composting process were determined as 43.9 degrees C, 43.9 degrees C and 53.7 degrees C in the R-1, R-2 and R-3 reactors, respectively. When the C/N ratios are examined, R-3, in which the C/N ratio had decreased at a rate of 18.5% by the end of the process and which had the highest temperature rise, can be defined as the best reactor. It has been found that the efficiency of the composting process of food industry treatment sludge and cattle manure is high.