Methods are described for the production of hydrogen-bis(chelato)borates of the general formula H[BL1L2] and of alkali metal-bis(chelato)borates of the general formula M[BL1L2] where M=Li, Na, K, Rb, Cs L1=—OC(O)—(CR1R2)n—C(O)O— or —OC(O)—(CR3R4)—O— where n=0 or 1, R1, R2, R3, R4 independently of one another denote H, alkyl, aryl or silyl, L2=—OC(O)—(CR5R6)n—C(O)O— or —OC(O)—(CR7R8)—O— where n=0 or 1, R5, R6, R7, R8 independently of one another denote H, alkyl, aryl or silyl, wherein the respective raw materials are mixed in solid form without the addition of solvents and are reacted. Lithium-bis(oxalato)borate, lithium-bis(malonato)borate, caesium-bis-(oxalato)borate, caesium-bis-(malonato)borate and the mixed salts lithium(lactato,oxalato)borate and lithium(glycolato,oxalato)borate for example may be produced in this way.