Sub‐micron homogeneous powders of YBa2Cu4O8havingTc∼80 K were synthesised from aqueous solutions containing Y, Ba, Cu salts, and oxalic acid as a precipitant via a chemical coprecipitation method using triethylamine as a base. An accelerated formation−within 24 h−of nearly single phase YBa2Cu4O8powders was achieved. The intragrain critical current density at 5 K andH=1 T was determined to be 3.9×107A/cm2. This process may have considerable potential in the large‐scale preparation of YBa2Cu4O8.