Thanks for your answer. I am using siRNA. Nuclerfactor could be a choice. However, I want to know whether there is a better chemical transfection method.
Several researchers have used cationic lipids (eg Dotap etc) and or polymers (polyethyleneimine) to achieve better transfection efficiencies in other cell types, you can try any of them.
I would try the most common lipid based transfection reagents like Lipofectamine etc. first, but if you do not succeed , I would recommend Electroporation which is known to work well with T-cells. Here is a link to a good start up protocol - http://mcmanuslab.ucsf.edu/protocol/lymphocyte-sirna-electroporation-transfection