Ceramic candle filters have been developed for cleaning high-temperature high-pressure (HTHP) gas streams. They meet environmental and economical considerations in combined cycle power plants, where gas turbine blades can be protected from the erosion that occurs due to using HTHP exhaust from the fluidized bed. Ceramic candle filters are the most promising hot gas filtration technology, which has demonstrated high collection efficiencies at high-temperature high-pressure conditions. This paper reports computational fluid dynamics (CFD) and experimental investigations of a candle filter. Experimentally, 18 and 1.08 mu m particles are tracked in the vicinity of a filter using Particle Imaging Velocimetry (PIV). The images are processed to give the radius of convergence, which defines the critical trajectory for particles just impinging on the filter. In the computational investigation, constant filtration velocity boundary models have been used to investigate the filter in cross flow conditions using the CFD code FLUENT. Different approach (inlet) velocity to filter face velocity ratios and different face velocities (ranging from 2-5 cm/s) are used in the CFD calculation. Particles in the diameter range 1-100 mu m are tracked through the domain. The radius of convergence is compared and plotted as a function of many parameters. Validation of the computational study in this work was adequate and the deposition process and the factors that affect the build up of the filter cake have also been studied.