A multiprotein complex, THO/TREX, couples the transcription, 3′‐end formation and nuclear export of mRNAs. In this study, we report that crucial factors for mRNA processing, such as XRN2, DDX5/DDX17 and CstF64, are copurified with human THO (hTHO). Using chromatin immunoprecipitation, we found increased cross‐linking of XRN2 and CstF64 to the RNA polymerase II (RNAP II) pause site of the HSPA1A gene upon down‐regulation of THOC5, a metazoan‐specific component of hTHO. As observed in THOC5‐depleted cells, knockdown of XRN2 blocked HSP70 transcript release and increased the amount of CstF64 at the pause site. In addition, our data indicate that DDX5/DDX17 is also required for HSP70 transcript release. As the degradation of read‐through transcripts, but not cleavage at polyadenylation sites per se, was hindered upon THOC5 or DDX5/DDX17 down‐regulation, these factors appear to influence transcriptional termination. Interestingly, over‐expression of RNase H suppressed the accumulation of HSP70 transcripts in nuclear foci in THOC5‐ or DDX5/DDX17‐depleted cells. Thus, we propose a model in which hTHO, along with DDX5/DDX17, restricts the formation of R‐loops, thereby facilitating the XRN2‐mediated transcriptional termination and release of the mature transcript from the HSPA1A locus.