In my library I have this code (yet used in another project) where pwork is assigned to a shared_ptr: -------------------------------------------------------------- typedef boost::shared_ptrboost::asio::io_service::work io_work_ptr; // Main io_service static boost::asio::io_service io_service; static boost::scoped_ptrboost::thread io_service_thread; static boost::asio::io_service::work* p_work; static bool thread_started; bool CreateMainThread() { if (!thread_started) { try { // create the work object on the heap p_work = new boost::asio::io_service::work(io_service); // run the IO service as a separate thread: io_service_thread.reset ( new boost::thread ( boost::bind ( &boost::asio::io_service::run, &io_service ) ) ); thread_started = !thread_started; return true; } catch (boost::thread_resource_error e) { // Failed to create the new thread return false; } } } -------------------------------------------------------------- WaveStream::WaveStream() : rx_timer_(io_service) { }; WaveStream::Test() { //Start a new timer or renew it rx_timer_.expires_from_now( boost::posix_time::milliseconds(500) ); // We managed to cancel the timer. Start new asynchronous wait. rx_timer_.async_wait( boost::bind(&WaveStream::handle_timeout, this, _1) ); } void WaveStream::handle_timeout(const boost::system::error_code& error) { .... } -------------------------------------------------------------- The timer callback is never called. Is there a way to know if the io_service is runing? Daniele.