An open top chamber experiment was conducted in Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore to know the effect of elevated Carbon dioxide (CO2) on plant growth, yield, yield attributes and nutrient uptake of rice and maize. Both the crops were grown under three Carbon dioxide levels viz., 376 µ mol mol-1 CO2 (C0), 550 µ mol mol-1 CO2 (C1) and 650 µ mol mol-1 CO2 (C2). Rice was grown in Irugur (S1) and Padugai (S2) soil series. Irugur soil series was clay loam in texture, taxonomically classified as Typic Ustropept. Padugai soil series was clayey in texture, taxonomically classified as Vertic Ustropept. Results revealed that plant growth parameters like plant height, number of tillers, yield attributes such as number of productive tillers, number of grains per panicle, number of filled grains per panicle, thousand grain weight, grain and straw yield were concomitantly increased from active tillering to harvesting stage. These parameters have high in 650 µ mol mol-1 CO2 than 376 µ mol mol-1 CO2. Padugai soil series recorded significantly higher plant growth parameters and yield attributes than Irugur soil series. Maize was grown in Palaviduthi (S1) and Periyanaickenpalayam (S2) soil series. Palaviduthi soil series was sandy 1oam in texture, taxonomically classified as Typic Rhodustalf. Periyanaickenpalayam series was sandy clay loam in texture, taxonomically classified as Vertic Ustropept. Among the soil series, Periyanaickenpalayam soil series (S2) recorded higher plant height, cob length, number of rows per cob, number of grains per cob, grain test weight, grain yield and stover yield compared to Palaviduthi soil series (S1). Comparison of CO2 levels indicated that, CO2 levels failed to attain the level of significance in growth and yield attributes. But, in both crops interaction between soil series and CO2 levels was failed to attain the level of significance.