Although colonic lumen NH₄⁺ levels are high, 15-44 mM normal range in humans, relatively few studies have addressed the transport mechanisms for NH₄⁺. More extensive studies have elucidated the transport of NH₄⁺ in the kidney collecting duct which involves a number of transporter processes also present in the distal colon. Similar to NH₄⁺ secretion in the renal collecting duct, we show that the distal colon secretory model, T84 cell line, has the capacity to secrete NH₄⁺ and maintain an apical to basolateral NH₄⁺ gradient. NH₄⁺ transport in the secretory direction was supported by basolateral NH₄⁺ loading on NKCC1, Na⁺/K⁺-ATPase, and the NH₄⁺ transporter, RhBG. NH₄⁺ was transported on NKCC1 in T84 cells nearly as well as K⁺ as determined by bumetanide-sensitive ⁸⁶Rb-uptake. ⁸⁶Rb-uptake and ouabain-sensitive current measurement indicated that NH₄⁺ is transported by Na⁺/K⁺-ATPase in these cells to an equal extent as K⁺. T84 cells expressed mRNA for the basolateral NH₄⁺ transporter RhBG and the apical NH₄⁺ transporter RhCG. Net NH₄⁺ transport in the secretory direction determined by ¹⁴C-methylammonium uptake and flux occurred in T84 cells suggesting functional Rh G protein activity. The occurrence of NH₄⁺ transport in the secretory direction within a colonic crypt cell model likely serves to minimize net absorption of NH₄⁺ due to surface cell NH₄⁺ absorption. These findings suggest that we rethink the current limited understanding of NH₄⁺ handling by the distal colon as being due solely to passive absorption.