The use of alternative fuels in Portland cement manufacturing reduces the amount of emissions such as CO2 and NOX gases. Also, it causes a considerable energy cost reduction. In addition, the use of alternative fuel has a positive impact on environment as a result of reduction of solid waste disposal. Therefore, the aim of this work is to investigate the effect of residual ashes produced from using RDF solid waste as biofuel in Portland cement manufacture on its properties. The solid waste used in this study is refuse derived fuel (RDF) mainly from municipal waste. The effect of adding different ratios of the ash, produced after burning such solid waste, to Portland cement on its hydration characteristics was investigated. This is done through the determination of standard water of consistency, initial and final setting times, compressive strength, chemically combined water content as well as the phase composition of the hydration products via the XRD examination. The ratios of ash used were: 0.0, 0.5, 1.0, 1.5 and 2.0% by weight of Portland cement. The samples with RDF ash showed relatively high values of compressive strength compared to blank sample at early ages of hydration up to 7 days.