Ground silica monolith particles of quite smaller average size (2 μm) have been prepared by sol-gel process followed by soft grinding and calcination. Next a highly efficient chromatographic stationary phase has been prepared by reaction of those particles with (3-chloropropyl) trimethoxysilane followed by initiator attachment and modification of polystyrene by reversible addition-fragmentation chain transfer polymerization. The resultant phase of ca 3 μm particle size was packed in micro-columns (1.0 mm × 300 mm & 1.0 mm × 150 mm) to show the separation efficiencies as high as 67,600 and 35,500 plates/ column, respectively, for the separation of 5 small test molecules at a mobile phase flow rate of 25 μL/min. The 300 mm column shows a separation efficiency better than any of the commercially available conventional packed columns so far. Multiple shapes and high surface roughness as well as reduced particle size of the stationary phase of this study seem to contribute to such enhanced separation efficiency.