In this Letter, the authors study analytical performance of various soft data fusion (SDF) schemes over generalised fading channels in a cognitive radio network. Two generalised fading models, namely, and are considered individually in the sensing channels and various SDF techniques are implemented at the fusion centre. Novel analytical frameworks for cooperative detection probability are developed subject to SDF and generalised fading and validated through computer simulations. Optimal values of the detection thresholds are determined where an average error rate is minimum.