Accurate BV(RI)c light and colour curves of the Mira variable in the dust-free symbiotic system K4-46 are presented and discussed. They cover several consecutive pulsations cycles. The Mira mean period is 284.2d, the reddening sums to E(B-V)=0.35 and the distance is 10kpc. Absolute spectrophotometry at both maximum and minimum brightness of the Mira is presented.