Rate coefficients for reactions of a series of α,β-unsaturated esters with OH and NO 3 radicals, O 3 and Cl atoms have been estimated using different methods: i.e., physico-chemical correlations and Structure Activity Relationships (SARs). In this study new correlations to estimate rate coefficients have been proposed (only for α,β-unsaturated esters): logkNO3 = (13.9 ± 2.8) + (2.75 ± 0.26) × log (k OH ); log (k OH ) = (4.93 ± 1.14) + (1.60 ± 0.12) × log (k Cl ); ln(k OH /cm 3 molecule −1 s −1 ) = (1.71 ± 0.21) × E HOMO /eV − (6.25 ± 2.24); ln(kNO3/cm 3 molecule −1 s −1 ) =(5.94 ± 0.35) × E HOMO /eV + (27.87 ± 3.65); ln(kO3/cm 3 molecule −1 s −1 ) = (2.20 ± 0.63) × E HOMO /eV − (16.75 ± 6.65) and ln(k Cl /cm 3 molecule −1 s −1 ) = (0.21 ± 0.23) × (E HOMO )/eV − (19.8 ± 2.4). The group reactivity factors necessary to estimate the rate coefficients by SAR methods have also been calculated for a series of α,β-unsaturated esters for the first time: f(–C(O)O(CH 2 ) 3 CH 3 ), f(–C(O)O(CH 2 ) 5 CH 3 ), f(–C(O)OCH 2 CH(CH 2 CH 3 )CH 2 CH 2 CH 2 CH 3 ) for reactions with the NO 3 radical, OH radical and O 3 . Furthermore, f(–C(O)OCH 3 ), f(–C(O)OCH 2 CH 3 ), f(–C(O)O(CH 2 ) 3 CH 3 ), f(–C(O)OCH 2 CH 2 CH 2 CH 2 CH 2 CH 3 ), f(–C(O)OCH 2 CH(CH 2 CH 3 )CH 2 CH 2 CH 2 CH 3 ) for reactions with chlorine atoms have been estimated.The results show that for NO 3 and OH radicals these methods are generally satisfactory. In the case of Cl atoms, all methods used in this study reproduce the rate coefficient within a factor of 1.5. In general the best method for estimating the rate coefficient of α,β-unsaturated esters with the main atmospheric oxidants is the correlation of ln k versus E HOMO .