The partial oxidation of 1,3-butadiene to furan was investigated on pure phases of alpha- and gamma-bismuth molybdate (BiMo) as well as on a mixture of 50% alpha-BiMo and gamma-BiMo. The kinetic measurements were carried out in an isothermal tube reactor with plug now assumed. Along the length of the catalyst bed the gas phase composition was analysed. The set-up of parallel and consecutive reactions with first-order kinetics made a mathematical modelling possible. Within a temperature range of 380 to 440 degrees C butadiene conversions of up to 75% were achieved. Main organic product was furan with a maximum yield of 11%.