Short RNA oligomers are required in many biochemical and biophysical studies. In vitro transcription using T7 RNA polymerase can produce a large amount of specific RNA sufficient for structural studies in a more economical way than chemical synthesis. Here, we provided protocols optimized for the synthesis of very short RNA of 10–20 nucleotides in length by in vitro transcription. These RNA oligomers can be purified conveniently by gel filtration chromatography. We also described how to study RNA and protein binding by gel filtration chromatography.