Objectives:　An　accurate　model　of　the　dynamic　contact　angle　theta(d)　is　critical　for　the　calculation　of　capillary　force　in　applications　like　enhanced　oil　recovery,　where　the　capillary　number　Ca　ranges　from　10(-10)　to　10(-5)　and　the　Bond　number　Bo　is　less　than　10(-4).　The　rate-dependence　of　the　dynamic　contact　angle　under　such　conditions　remains　blurred,　and　is　the　main　target　of　this　study.　Experiments:　Featuring　with　pressure　control　and　interface　tracking,　the　innovative　experimental　system　presented　in　this　work　achieves　the　desired　ranges　of　Ca　and　Bo,　and　enables　the　direct　optical　measurement　of　dynamic　contact　angles　in　capillaries　as　tiny　as　40　x　20　(width　x　height)　mu　m　and　80　x　20　mu　m.　The　advancing　and　receding　processes　of　wetting　and　nonwetting　liquids　were　tested.　Findings:　The　dynamic　contact　angle　was　confirmed　velocity-independent　with　10(-9)　＜　Ca　＜　10(-5)　(contact　line　velocity　V　=　0.135-490　mu　m/s)　and　it　can　be　described　by　a　two-angle　model　with　desirable　accuracy.　A　modified　two-angle　model　was　developed　and　an　empirical　form　was　obtained　from　experiments.　For　different　liquids　contacting　the　same　surface,　the　advancing　angle　theta(adv)　approximately　equals　the　static　contact　angle　theta(o).　The　receding　angle　theta(rec),　was　found　to　be　a　linear　function　of　theta(adv),　in　good　agreement　with　our　and　other　experiments　from　the　literature.　(C)　2018　Elsevier　Inc.　All　rights　reserved.