The prompt gamma-rays from thermal nuteron capture in {sup 28,29,30}Si have been studied and the radiative capture cross sections determined as 207{plus minus}4, 120{plus minus}3 and 107{plus minus}2 mb, respectively. There has been a marked increase in the number of transitions observed in {sup 29}Si and a complete decay scheme for this nucleus is presented. Two primary {ital E}2 transitions in {sup 29}Si have been observed and their partial cross sections are compared with the prediction of the direct capture formalism. The measured neutron separation energies are {ital S}{sub {ital n}}({sup 29}Si)=8473.61{plus minus}0.04 keV, {ital S}{sub {ital n}}({sup 30}Si)=10 609.21{plus minus}0.04 keV, and {ital S}{sub {ital n}}({sup 31}Si)=6587.32{plus minus}0.20 keV.