The　Industrial　Internet　of　Things　(IIoT)　has　provided　a　promising　opportunity　to　build　digitalized　industrial　systems.　A　fundamental　technology　of　IIoT　is　the　radio-frequency　identification　(RFID)　technique,　which　allows　industrial　participants　to　identify　items　and　anchor　time-series　IoT　data　for　them.　They　can　further　share　the　IoT　data　through　the　cloud　service　to　enable　information　exchange　and　support　critical　decisions　in　production　operations.　Storing　IoT　data　in　the　cloud,　however,　requires　a　data　access　control　mechanism　to　protect　sensitive　business　issues.　Unfortunately,　using　traditional　cryptographic　access　control　schemes　for　time-series　IoT　data　face　severe　efficiency　and　key　leakage　problems.　In　this　article,　we　design　a　secure　industrial　data　access　control　scheme　for　cloud-assisted　IIoT.　Our　scheme　enables　participants　to　enforce　fine-grained　access　control　policies　for　their　IoT　data　via　ciphertext　policy-attribute-based　encryption　(CP-ABE)　scheme.　Our　scheme　adopts　a　hybrid　cloud　infrastructure　for　participants　to　outsource　expensive　CP-ABE　tasks　to　the　cloud　service　with　strong　privacy　guarantees.　Importantly,　our　scheme　guarantees　a　new　privacy　notion　named　item-level　data　protection　for　IoT　data　to　prevent　key　leakage　problem.　We　achieve　these　goals　via　several　encryption　and　optimization　techniques.　Our　performance　assessments　combine　system　implementation　with　large-scale　emulations　and　confirm　the　security　and　efficiency　of　our　design.　©　2014　IEEE.