The characteristics of the particle flow in a horizontal pipe following a 90 degrees vertical-to-horizontal elbow were investigated both numerically and experimentally. Laboratory experiments were conducted in a 0.154 m LD test section. The effects of air velocity, the ratio of air-to-solids mass flow rate, geometry of the elbow and inlet conditions on gas-solid flow patterns were investigated experimentally. Pulverized coal with a mean particle diameter of 50 mum was used as the solid material. Experiments were performed with conveying air velocities ranging from 15 to 30 m/s and air-to-solids mass flow rate ratios of 1 and 3, with elbows having bend radius to pipe diameter ratios of 1.5 and 3.