Relative Rate (RR) technique was used for the measurement of OH-initiated photo-oxidation reactions of Ethyl 2-methyl propionate (E2MP) and Ethyl-2,2-dimethyl propionate (E22DMP) in the temperature range of 268-363 K at 760 Torr. In addition to this, the thermodynamic and kinetic parameters for the title reactions were theoretically investigated using CCSD(T)/cc-pVTZ//M06-2X/6-311++G(2d,2p) level of theory in the temperature range of 200-400 K using Canonical Variational Transition State theory (CVT) in combination with Small Curvature Tunneling (SCT) method. The rate coefficients at (298±2) K were measured to be kE2MP + OH = (2.71±0.79) × 10-12 cm3 molecule-1 s-1 and kE22DMP + OH = (2.58±0.80) × 10-12 cm3 molecule-1 s-1. The degradation mechanisms for the title reactions were investigated in the presence of O2 using Gas Chromatography with Mass Spectrometry (GC-MS) and Gas Chromatography with Infrared Spectroscopy (GC-IR). From the recognized products, the possible product degradation mechanisms were predicted. In addition to this, the atmospheric lifetimes (ALs), lifetime-corrected Radiative Forcing (RF), Global Warming Potential (GWPs) and Photochemical Ozone Creation Potentials (POCPs) were calculated to further understand the environmental impact of these molecules on the Earth’s troposphere.