Deconvolution of bulk transcriptomics data from mixed cell populations is vital to identify the cellular mechanism of complex diseases. existing deconvolution approaches can be divided into two major groups: supervised and unsupervised methods. Supervised deconvolution methods use cell typespecific prior information including cell proportions, reference cell type-specific gene signatures, or marker genes for each cell type, which may not be available in practice. Unsupervised methods, such as non-negative matrix factorization (nMf) and convex Analysis of Mixtures (cAM), in contrast, completely disregard prior information and thus are not efficient for data with partial cell type-specific information. in this paper, we propose a semi-supervised deconvolution method, semi-cAM, that extends cAM by utilizing marker information from partial cell types. Analysis of simulation and two benchmark data have demonstrated that semi-cAM outperforms cAM by yielding more accurate cell proportion estimations when markers from partial/all cell types are available. in addition, when markers from all cell types are available, semi-cAM achieves better or similar accuracy compared to the supervised method using signature genes, ciBeRSoRt, and the marker-based supervised methods semi-nMf and DSA. furthermore, analysis of human chlamydia-infection data with bulk expression profiles from six cell types and prior marker information of only three cell types suggests that semi-CAM achieves more accurate cell proportion estimations than cAM.