Abstract Investigation of the effects of oxygen absorption on the two types of single walled silicon carbide nanotubes (SWSiCNTs) with different chiral angles were done. Our calculations were performed using density functional theory with quantum ESPRESSO and YAMBO codes. Changes in electrical and optical properties were analyzed after introducing two molecules of oxygen as absorbing gas to both armchair and zigzag nanotubes. Results demonstrated a new future by SWSiCNT in which oxygen absorption significantly closes the band gap which transformed the materials from semiconducting to metallic. This future revealed its potential for application as automobile gas switches for air conditioners. Results from optical calculations revealed that zigzag SiCNT is not optically potential above 20 eV, generally, the (6, 6) SWSiCNT demonstrate higher transmission with and without oxygen absorption in the ultraviolet region. The first absorption peaks appeared within the range of 1 eV to 3.4 eV for all systems, there is higher absorption by the oxygen absorbed (6, 6) SWSiCNT than the oxygen absorbed (6, 0) SWZSiCNT. This demonstrates that armchair form of SWSiCNT absorbs gases more than the zigzag form. The absorption peaks can be seen to fall above 3.5 eV and then rise again up to 10 eV, this behavior justifies the nanotubes potential in automobile day light sensors.