A method for selecting and providing a binding pair of single-stranded all-LNA oligonucleotides capable of forming in aqueous solution at a temperature from 0 °C to 40°C an antiparallel duplex with 5 to 15 consecutive base pairs, the method comprising the steps of (a) providing a first single-stranded (= ss-) oligonucleotide consisting of 5 to 15 locked nucleic acid (= LNA) monomers, each monomer comprising a nucleobase, the nucleobases of the first ss-oligonucleotide forming a first nucleobase sequence; (b) providing a second ss-oligonucleotide consisting of 5 to 15 LNA monomers, the second ss-oligonucleotide comprising at least the number of monomers as the first ss-oligonucleotide, each monomer of the second ss-oligonucleotide comprising a nucleobase, the nucleobases of the second ss-oligonucleotide forming a second nucleobase sequence, the second nucleobase sequence comprising or consisting of a nucleobase sequence complementary to the first nucleobase sequence in antiparallel orientation and predicting the capability of the first and second ss-oligonucleotide to form with each other an antiparallel duplex, the predicted duplex comprising or consisting of 5 to 15 consecutive base pairs, wherein the two bases of each base pair are bound to each other by hydrogen bonds; (c) mixing in an aqueous solution about equal molar amounts of the first and second ss-oligonucleotide; (d) incubating the mixture of (c) for a time interval of 20 min or less, thereby obtaining a mixture still comprising the first and second oligonucleotide as ss-oligonucleotides or a mixture containing or consisting of the first and second oligonucleotide as duplex; (e) detecting and quantifying in the mixture obtained in step (d) ss-oligonucleotides and duplex oligonucleotides; followed by (f) selecting the binding pair if in step (e) duplex is detectably present, and the molar amount of duplex is higher than the molar amount of ss-oligonucleotides; (g) optionally synthesizing separately the first and the second ss-oligonucleotide of a binding pair selected in step (f); thereby selecting and providing the binding pair of single-stranded all-LNA oligonucleotides, wherein steps (c) and (d) are performed at a non-denaturing temperature selected from the group consisting of 0 °C to 5 °C, 5 °C to 10 °C, 10 °C to 15 °C, 15°C to 20 °C, 20 °C to 25 °C, 25 °C to 30 °C, 30 °C to 35 °C, and 35 °C to 40 °C. (a) providing a first single-stranded (= ss-) oligonucleotide consisting of 5 to 15 locked nucleic acid (= LNA) monomers, each monomer comprising a nucleobase, the nucleobases of the first ss-oligonucleotide forming a first nucleobase sequence; (b) providing a second ss-oligonucleotide consisting of 5 to 15 LNA monomers, the second ss-oligonucleotide comprising at least the number of monomers as the first ss-oligonucleotide, each monomer of the second ss-oligonucleotide comprising a nucleobase, the nucleobases of the second ss-oligonucleotide forming a second nucleobase sequence, the second nucleobase sequence comprising or consisting of a nucleobase sequence complementary to the first nucleobase sequence in antiparallel orientation and predicting the capability of the first and second ss-oligonucleotide to form with each other an antiparallel duplex, the predicted duplex comprising or consisting of 5 to 15 consecutive base pairs, wherein the two bases of each base pair are bound to each other by hydrogen bonds; (c) mixing in an aqueous solution about equal molar amounts of the first and second ss-oligonucleotide; (d) incubating the mixture of (c) for a time interval of 20 min or less, thereby obtaining a mixture still comprising the first and second oligonucleotide as ss-oligonucleotides or a mixture containing or consisting of the first and second oligonucleotide as duplex; (e) detecting and quantifying in the mixture obtained in step (d) ss-oligonucleotides and duplex oligonucleotides; followed by (f) selecting the binding pair if in step (e) duplex is detectably present, and the molar amount of duplex is higher than the molar amount of ss-oligonucleotides; (g) optionally synthesizing separately the first and the second ss-oligonucleotide of a binding pair selected in step (f); thereby selecting and providing the binding pair of single-stranded all-LNA oligonucleotides, wherein steps (c) and (d) are performed at a non-denaturing temperature selected from the group consisting of 0 °C to 5 °C, 5 °C to 10 °C, 10 °C to 15 °C, 15°C to 20 °C, 20 °C to 25 °C, 25 °C to 30 °C, 30 °C to 35 °C, and 35 °C to 40 °C.