Abstract: Disclosed is a horizontal extensometer for measuring strain on specimens in cryogenic to elevated temperatures with zero frictional and activation forces. The extensometer has first and second elongate hollow arms which are adapted to pivot in relation to one another in response to the increase in length of a test specimen when a strain is applied thereto. An increase between the points of attachment on the specimen produces a corresponding decrease in length at the opposite ends of the two arms, thereby producing movement through a standard linear variable differential transformer. A connecting rod which is highly rigid in the Y-axis but readily flexible in the Z and X-axes is adapted to pass through the center of the linear variable differential transformer to a moveable core and produce a measurement of the differential. The extensometer also employs a unique clamping mechanism which substantially reduces error caused by external forces. The extensometer of the present invention has near zero hysteresis.