Novel polyester glycols and novel chain extenders were used for the improvement of thermal stability and hydrolytic stability of polyurethane elastomers. The novel polyesterglycols are poly(β-methyl-δ-valerolactone)glycol (PMVL), poly(3-methyl pentamethylene adipate)glycol (PMAP), and novel poly(alkylene carbonate)glycol (PNOC) which is a random copolymer of 1,9-nonamethylene diol(ND; 30 mol %) and 2-methyl octamethylene glycol (MOD; 70 mol %). These polymer glycols have side methyl groups. Novel chain extenders are 1,4-cyclohexane diol(CHD), 1,4-cyclohexane dimethanol (CHDM), hexafluoro bisphenol-A(AF), 2,2-bis (4-aminophenyl) hexafuluoro propane(A-FA), and 2,2-bis (4-(4-aminophenoxy)phenyl) hexafluoro propane (AF-A). The mixture of these compounds with trimethylol propane were also used as a novel bimodal chain extender. Polyurethane network elastomers were prepared from 2,4-tolylene diisocyanate, these polymer glycols, and these chain extenders by using a prepolymer method. Mechanical properties, Tg, thermal stability, and hydrolytic stability were measured. The properties of novel polyurethane elastomers based on PMVL, PMPA, and PNOC were compared with those of general purpose polyurethane elastomers based on PCL and PBA. These novel polyurethanes had good mechanical properties comparable to those of the general purpose polyurethanes. Hydrolytic resistance of these novel polyurethanes was better than those of general purpose polyurethanes. The effect of water uptake on mechanical properties of the novel polyurethane elastomers was discussed. The effect of novel chain extenders on thermal and hydrolytic stability of novel polycarbonate polyurethane elastomers based on PNOC glycol was also discussed. The aromatic diamines/glycol containing fluoro methyl groups as a chain extender gave good mechanical properties, good thermal stability, and hydrolytic stability to the novel polyurethane elastomers. Especially, PNCO-TDI-AF-A/TMP PUE had rubber plateau range from room temperature to 230°C.