This study aimed to establish the properties of lightweight cement composites with organic fillers, such as common reed and conifer sawdust. The reed Phragmites australis is a notably common plant in Poland that grows on waterlogged lands, and sawdust is a waste product that appears during the mechanical processing of wood.The first step was to determine the influence of the mineralisation on the water absorbability of the organic filler. Next, the influences of the superplasticiser (SP) content and the method of mixture consolidation on cement composite properties, such as the compressive strength, the water absorbability, the density and the porosity structure, were established. The chemisorption abilities of the cement composite and of the organic filler were also determined.