The invention relates to a method of immobilising at least one RNA molecule onto a surface of a support comprising: i) providing a first support having a surface on which at least one DNA molecule is immobilised, wherein the DNA molecule encodes an RNA molecule and the encoded RNA molecule comprises a binding molecule; ii) providing a second support having a surface on which at least one binding partner for interacting with the binding molecule is immobilised; iii) arranging the first and second supports such that the surfaces displaying the immobilised molecules are in close proximity and substantially face each other, and contacting the DNA molecule immobilised on the surface of the first support with transcription reagents; and iv) carrying out a transcription reaction to generate the encoded RNA molecule, wherein the RNA molecule is directly immobilised onto the surface of the second support via an interaction between the binding molecule of the RNA molecule and the binding partner on the surface of the second support.