In this study, the effect of two water reducer polymers on the thermal stability, rheology, and compressive strength of Gasin Ordinary Cement (GC) was investigated. The behavior of cement in the liquid phase (slurry) and hardened phase modified with two types of polymer varied from 0 to 0.06% (%wt) were investigated. XRD and TGA tests were conducted to identify the effect of polymers on the behavior of GC. The compressive strength of cement mixed with polymers was tested from the early aged of 1 days to 28 days of curing. The shear stress versus shear strain rate of cement slurry was modeled and the results of prediction using Vipulanandan rheological model were compared to the Vocadlo model. High reduction in the total weight loss of the GC at 800 °C when the cement modified with 0.06% of polymers detected using TGA test. The rheological properties of the cement slurry such as viscosity, yield stress, and the compressive strength of GC were increased significantly with increasing the polymer contents. Addition of polymers reduced the required water to reach the desired fluidity by about 43% based on the type of polymer. The results showed that the Vipulanandan rheological model predicted the shear-thinning relationship between the shear stress and shear strain rate of the cement slurry modified polymers very well. Also, the Vipulanandan rheological model has a maximum shear stress limit were as the Vocadlo model did not have a limit on the maximum shear stress. Based on the Vipulanandan rheological model the maximum shear stress produced by the cement slurry modified with 0% and 0.06% of polymers at the temperature of 25 °C were increased from 38.7 to 171.3 Pa and to 184.8 Pa respectively due to the addition of polymers. Nonlinear models were used to separate the effect polymer quantity, water–cement ratio, and curing time on the rheological properties and compressive strength of cement.