A method of making nanosized copper (I) compounds, in particular, copper (I) halides, pseudohalides, and cyanocuprate complexes, in reverse micelles or microemulsions is disclosed herein. The method of the invention comprises (a) dissolving a copper (II) compound in the polar phase of a first reverse micelle or microemulsion, (b) dissolving a copper (II) to copper (I) reducing agent or a pseudohalide salt in the polar phase of a second sample of the same reverse micelle or microemulsion, (c) mixing the two reverse micelle/microemulsions samples to form nanometer sized copper (I) compounds and (d) recovering said nanometer sized copper (I) compounds. The present invention is also directed to the resultant nanosized copper (I) compounds, such as copper (I) chloride, copper (I) cyanide, and potassium cyanocuprate complexes having an average particle size of about 0.1 to 600 nanometers.