The continuous increase in the amount of residues generated by agricultural, industrial, and urban activities necessitates effective waste management methods. One of the emerging methods for waste reuse is incorporating residues as fillers in polymer composites. This study aimed to investigate the influence of the coal processing originated fillers, microspheres and fluidized-bed combustion fly ash, on the structure and properties of composite rigid polyurethane foam. Polyurethane foams were produced through manual mixing and casting method. Composite foams contained two types of fillers mixed together i.e. 5 wt. % of microspheres and 5, 10, or 15 wt. % of fly ash. The composite materials were subsequently examined to analyze their cellular structure using optical microscopy and image processing software. All samples were composed of mostly pentagonal, regular-in-shape cells. Their diameters ranged between 120 and 190 µm. Infrared spectroscopy was used to analyze the chemical composition of the foams. There were no observable chemical bonds formed between the matrix and filler materials. Mechanical analysis was conducted to assess the mechanical characteristics of the materials. The compressive strength and Young’s modulus showed considerable variation, ranging from 140 to 280 kPa and from 2.5 to 5.0 MPa, respectively. The results indicated that adding the filler did not impact the cellular and chemical composition of the polyurethane matrix. Composite material specimens underwent accelerated aging in a laboratory dryer and were exposed to outdoor conditions by being placed outside the building for a certain duration. The outcomes of these experiments exhibited significant alterations in both the cellular composition and mechanical characteristics of the composite foam materials.