The authors have been developing a novel threshold Cherenkov detector, consisting of a gas radiator followed by a UV photosensitive wire chamber using CsI photocathodes. The photo-detector lies directly in the particle path and is thus required to have single photo-electron sensitivity and yet to be insensitive to the passage of a charged particle. In addition, the detector should be made of low mass material to minimize the effect of multiple scatterings. The proposed threshold Cherenkov counters are called Hadron Blind Detectors (HBDs) because they are blind to low energy hadrons which have lower speed {beta} for given momentum p than that of electrons. HBDs can be used in colliders, especially heavy ion hadron colliders (RHIC, LHC), which have huge {number_sign} of hadrons produced per event, to select electrons by being blind to low-momentum hadrons. The authors have studied two different methods to build HBDs described as follows: (1) windowless configuration; (2) thin window configuration. The authors describe herewith their recent experimental results on HBD research obtained with CsI photo-cathodes and HBD prototype beam testing in 1995.