Recent advances in high-performance liquid chromatography (HPLC) columns have focused on various approaches to increase the speed of analyses. Monolithic columns, for example, were introduced for their potential for use at high mobile phase velocities due to decreased mass transfer effects over conventional fully porous particles. More recently, ultra-high performance chromatography on sub 2 μm particles have provided increased speed and efficiencies over conventional particles at the expense of high backpressures and, at times, column ruggedness. Fused Core� Technology is the next significant breakthrough in column technology aimed at reducing analyses time through increased efficiencies. The fused core technology breakthrough is based on a solid 1.7 μm core particle fused to a 0.5 μm outer shell of porous silica. The reduced intraparticle flow path results in significantly less diffusion within the confines of the analytical column. The result is similar column efficiencies to columns packed with sub 2 μm particles with about half the backpressure. Consequently, sub 2 μm-like efficiencies can be realized using conventional instrumentation. Additionally, the kinetic advantages of the fused core particle provide superior efficiencies to columns packed with conventional porous 3 μm particles, while creating only moderate backpressures. In this report we introduce the Fused-Core Technology and discuss its advantages through fundamental kinetic discussions and chromatographic examples. Improved speed, sensitivity, overall separation power and ruggedness will be highlighted.