The development of a suitable semen extender is required to extend artificial breeding programs and to preserve the genetic potential of Bactrian camel. Experiments were conducted to provide the optimal osmolality and pH of tris-based extender and to compare that with available extenders for short-term preservation of Bactrian camel semen at 4 degrees C during 24 h. In experiments I and II, the effects of varying osmolalities (270, 300, 330, 360, and 390 mOsm/kg) and pHs (5.5, 6, 6.9, 7.5, 7.9, and 8.9) of tris-based extender on sperm viability were investigated. In experiment III, the efficiency of tris-based extender (SHOTOR diluent) in preserving Bactrian camel semen was compared with lactose (10%), sucrose (10%) and Green buffer. Viability parameters including progressive forward motility (PFM), plasma membrane integrity and the percentage of live spermatozoa were assessed. The data were analyzed using general linear model procedure. In the majority of assessments using tris-based extender, the viability of spermatozoa was superior at the osmolality of 330 mOsm/kg and pH of 6.9. PFM was significantly greater at the time of semen dilution in tris-based (65.5%) and Green buffer (60.5%) compared to that of lactose (31%) and sucrose (28%) extenders (P<0.05), and remained elevated throughout the experiment. There was no significant difference in other viability parameters among 4 extenders (P>0.05). In conclusion, the utilization of a tris-based extender, having the osmolality of 330 mOsm/kg and pH of 6.9, favors the short-term preservation of the Bactrian camel spermatozoa under chilled condition.