Microalgae are an interesting alternative in renewable energy production and for carbon dioxide capturing and cleaning of flue gas from power, cement, or steel plants. The low CO2 partial pressure of the atmosphere can be compensated by using industrial flue gas, thereby increasing algal growth and decreasing flue gas pollution. Flue gas is a mixture of toxic and non-toxic gases, such as CO2 and different particles. Prior to establishing a flue-gas treated algae culture, the effect of flue gas constituents on algal production needs to be tested. A tubular photobioreactor, TPBR, was designed to compare the effects of flue gas from Cementa AB Degerhamn, (Heidelberg Cement) in the South of Öland (SE Sweden), to air controls and a synthetic AGA prepared CO2/air mixture (13.5 % CO2) on the green alga Tetraselmis sp. (KAC 21), isolated from the Baltic Sea. Batch cultures of Tetraselmis sp. received flue gas and synthetic AGA gas in separate runs with air controls in triplicates. Flue gas and synthetic AGA gas was injected to the TPBR every 24 hours during a period of 10 days. During the 10 day period all cultures depleted the nutrient concentration to more than 98 %. Flue gas had a positive effect on algal growth, despite the potentially toxic substances. Dry weight, cell density, optical density, growth rate and productivity were higher compared to the air control. These results demonstrate that neither nitrogen oxides (NOx) nor sulfur oxides (SOx) contained in the cement flue gas were toxic to the algae. Tetraselmis sp. exposed to flue gas reached average maximum growth rates of 1.10 doublings day-1, with productivity reaching 0.057 g dry weight L^-1 day^-1. The algal growth rate and productivity were however most likely underestimated as the TPBR suffered from random bio-fouling, thus diminishing the yield.