Poly(N-isopropylacrylamide), one of the most utilized thermoresponsive polymers, brush-grafted monolithic-silica columns were prepared through surface-initiated atom transfer radical polymerization (ATRP) for effective thermo-responsive-chromatography matrices. ATRP initiator was grafted on monolithic silica-rod surfaces by flowing a toluene solution containing ATRP initiator into monolithic silica-rod columns. N-Isopropylacrylamide (IPAAm) monomer and CuCl/CuCl(2)/ Me(6)TREN, an ATRP catalytic system, were dissolved in 2-propanol, and the reaction solution was pumped into the preprepared initiator-modified columns at 25 degrees C for 16 h. The constructed PIPAAm-brush structure on the monolithic silica rod surface was confirmed by XPZ, elemental analysis, SEM observation, and GPC measurement of grafted PIPAAm. The prepared monolithicsilica-rod columns were also characterized by chromatographic analysis. PIPAAm-brush-modified monolithic silica-rod columns were able to separate hydrophobic steroids with a short analysis time (10 min), compared to PIPAAm-brush-modified silica-beads-packed columns, because of the horizontally limited diffusion path length of monolithic supporting materials Additionally, diluted PIPAAm-brush monolithic silica rod column gave a further shorting analysis time (5 min). These results indicated (1) surface initiated ATRP constructed PIPAAm-brush structures on monolithic silica rod surfaces and (2) PIPAAm-brush grafted monolithic silica rod column prepared by ATRP was a promising tool for analyzing hydrophobic-bioactive compounds with a short analysis time