We estimate proton and alpha particle bulk parameters within the cometosheath. Temperature of protons seems to decrease from bow shock to about 2×10^5km (not at closest approach), and increase thereafter slightly. This decrease is likely caused by the cooling effect accompanying with the charge exchange process as well as with the mass addition of cold pickup ions. On the contrary, the observed temperature of alpha particles stayed almost constant throughout the cometosheath. We attribute this to the absence of effective cooling process for alpha particles within the cometosheath.