Abstract: The gaseous detonation of 2H_2/O_2/Ar mixturepropagation through a T-shape bifurcated tube with a square cross-section40\,mm\times 40\,mm has been experimentally studied in this paper. Thepressure histories at the specific ports were recorded by pizeo-electrictransducers and cellular patterns around the T-shape were recorded by smokedfoils respectively. The average velocity of detonation and the cellevolution were obtained. Experimental results indicate that the detonationwave is strongly weakened by the geometry around the T-shape tube. Theinteractions of leading shock and transverse waves contribute to thetraveling characteristics of detonation. In the downstream region far awayfrom 3.5 to 6 times the tube cross-section size, a secondary steadydetonation wave is re-established accompanying the appearance of regularcellular structures with the same sizes as the previous one. The cellularpatterns also demonstrate the phenomena of diffraction, regular and Machreflections of gaseous detonation. In the pass-by tube, it is noted that thecellular structure disappears in the region just downstream the start of theT-shape due to the separation of leading shock and reaction zone. With thepropagation and reflection of the leading shock in the pass-by tube, there-initiation occurs in the separated region between the leading shock andreaction zone. The re-initiation can be demonstrated by the clusteredcellular structures on the smoked-foils, and it is critical inre-establishing of gaseous detonation here. As the initial pressuredecreases to 2.00\,kPa, the steady detonation can be re-established indownstream region, but detonation extinguishes in the bifurcated tube. Also,based on the smoked foil records, several characteristic lengths and angleswere measured and the initial pressure influences on them were analyzed.